docs(readme): replacement guide + a verified seed example (t41)

The README now answers the question a migrator actually has: what do I delete,
and what covers it afterwards.

* a new "Replacing androidtv / androidtv_remote + the glue" section: the
  back-up → remove-the-platform-YAML → remove-mediasession2mqtt → delete the old
  integrations → add this one → update automations checklist, plus a table
  mapping every retired piece to what serves it now. It notes that Wholphin
  publishes no MediaSession of its own and gets its now-playing from the ADB
  media session, so no bridge is needed for it either;
* the setup steps describe the real flow (name + one address, both transports on
  by default, ADB pairing then PIN pairing, each with a skip);
* the YAML seed section carries a complete, copy-pasteable block. It documents
  ONLY the keys `_yaml_seed_blocks` honours (name, host, adb_port, adb_enabled,
  and the still-accepted protocol_host/adb_host) and says explicitly that the
  rest lives on the Configure page — an example that lists ignored keys is worse
  than no example;
* the state-ladder section, the discovery bullet and the options list follow the
  two-transport, one-address reality.

`tests/test_readme.py` pins the doc/code contract: the example's keys are a
subset of what the seed reads, the example uses the current `host` key, and the
guide keeps naming the retired integrations and glues.

Verified: 326 passed / 2 skipped, ruff clean.

README.md

@@ -79,10 +79,15 @@ TiviMate (`ar.tvplayer.tv`) is the documented no-session case: it publishes
 no MediaSession on Shield Android 11 (RESEARCH_SHIELD R2), so tiers 6–7 plus
 the audio hint are what keep it visible.
 
-**Standalone setup** accepts any one of the three state sources — the Android
-TV Remote entity, the Nvidia Remote Protocol (PIN pairing), or ADB
-media-session mode (ADB enabled + host). The `no_state_source` form error
-fires only when none of the three is present; ADB-only setups are valid.
+**Standalone setup** offers both state sources at once — the Nvidia Remote
+Protocol (PIN pairing) and ADB media-session mode — enabled by default, with the
+Shield's address pre-filled when discovery found it. Either can be turned off,
+and each pairing step can be skipped (that transport stays off until you pair
+it), so ADB-only, protocol-only and fully passive entries are all one click
+apart. The `no_state_source` form error fires only when neither is enabled.
+
+There is no other integration in the loop: one address, two transports, and the
+integration reads the device itself.
 
 ### Channel entry options
 
@@ -96,17 +101,32 @@ behavior). Both are consumed by `play_media` with
 
 An optional `nvidia_shield:` block in `configuration.yaml` **seeds** an
 interactive setup flow — nothing is created without the user walking the
-standard flow, and pairing stays interactive exactly as with UI setup:
+standard flow, and pairing stays interactive exactly as with UI setup. The UI is
+the primary path; the block exists so a provisioning/fleet setup can supply the
+address and the transport choice.
+
+A complete, copy-pasteable block (every key is optional except an address):
 
 ```yaml
 nvidia_shield:
-  - name: Living Room
-    adb_host: 10.0.0.31      # or protocol_host for the PIN-pairing hint
-    adb_port: 5555
+  - name: Living Room        # the entry's title (default: NVIDIA Shield)
+    host: 10.0.0.31          # the Shield's IP — the one address field
+    adb_port: 5555           # optional; the standard ADB port
+    adb_enabled: true        # optional; the block's shape decides (see below)
 ```
 
-`protocol_host` is a prefill hint only (the PIN pairing still happens in
-the flow). Blocks without protocol/adb hosts are ignored with a warning.
+`host` is the current key. `protocol_host` and `adb_host` are **still accepted**
+(protocol first, then ADB) so an existing `configuration.yaml` keeps seeding:
+the address is a prefill hint either way, and the PIN/ADB pairing still happens
+in the flow. `adb_enabled` defaults to what the block implies — an address under
+`host`/`adb_host` marks ADB as part of the block, a protocol-only block leaves it
+off — and an explicit `adb_enabled` wins over the shape. Blocks without any
+address are ignored with a warning.
+
+The seed carries the address, the ADB toggle and the entry's name; everything
+else (Jellyfin, receiver, power switch, app name/icon maps, channel timing, the
+`adb_command` service) is set on the entry's **Configure** page after setup, or
+during the interactive flow.
 Duplicate guards: a block matching an existing entry's host (or its
 virtual `yaml:…` unique_id) aborts and never re-seeds a UI-configured
 host. Removing the YAML block creates or deletes nothing — entries live
@@ -126,15 +146,45 @@ documented, opt-in escape hatch for debugging and automation, registered at
 setup and unregistered when the last participating entity unloads. It
 rejects (logs a warning, sends nothing) when the ADB connection is down.
 
-### Migration from mediasession2mqtt + universal-player glue
+## Replacing androidtv / androidtv_remote + the glue
 
-The `mediasession2mqtt` bridge sensors and the universal media player YAML
-templates the fork replaces are retired by the ladder above: the media player
-entity already carries the DAG attributes (`media_dag_running_apps` with
-foreground/last-known enrichment, `media_dag_now_playing` with its source
-tag) that media-zone orchestration consumed from those sensors. See the
-appendix in [`docs/RESEARCH_SHIELD.md`](docs/RESEARCH_SHIELD.md) for the
-retirement mapping and the universal-player glue it replaces.
+This fork replaces the old `androidtv` media player, the `androidtv_remote`
+integration and the surrounding YAML glue — there is nothing to keep alongside
+it: the entry's own two transports cover the whole device.
+
+1. **Back up** your `configuration.yaml` and note the Shield's IP address.
+2. **Remove the old platform YAML** — the `media_player:` blocks using
+   `platform: androidtv` or `platform: androidtv_remote`, any `universal` media
+   player template that fanned them in, and the `remote:`/`switch:` shims you
+   added around them.
+3. **Remove the `mediasession2mqtt` bridge** — its sensors and the MQTT topics
+   feeding them are replaced by this integration (table below).
+4. **Delete the old integrations** in Settings > Devices & Services, then
+   **restart** Home Assistant.
+5. **Add this integration** — Settings > Devices & Services > Add Integration >
+   "NVIDIA Shield" — or seed it from `configuration.yaml` with the block above,
+   then walk the pairing steps.
+6. **Update your automations and dashboards** to the new entities:
+   `media_player.<entry>`, `remote.<entry>`, `sensor.<entry>_current_app`,
+   `sensor.<entry>_now_playing`, and the `media_dag_*` attributes.
+
+What each retired piece used to provide, and what covers it now:
+
+| Retired piece | Covered by |
+|---------------|------------|
+| `androidtv` playback state | the ADB media-session state ladder (`playing` / `paused` / `idle` / `off`) |
+| `androidtv` app name / `app_id` lookups | the manager's store + the app-name map + the manifest label of the running app |
+| `androidtv_remote` power, volume and key commands | the protocol transport: the `remote` entity, `media_player` volume, `KEYCODE_*` commands |
+| `androidtv_remote` availability | the availability contract (protocol `is_on`, ADB awake, power switch) |
+| `universal` media player templates | the media player entity's own attributes plus the `media_dag_*` attributes |
+| `mediasession2mqtt` sensors | `sensor.current_app`, `sensor.now_playing` and the `media_dag_*` attributes |
+
+**Wholphin** publishes no MediaSession metadata of its own; its now-playing
+comes from the ADB media session — the same tier every other app uses — so it
+needs no bridge either.
+
+The appendix in [`docs/RESEARCH_SHIELD.md`](docs/RESEARCH_SHIELD.md) holds the
+full retirement mapping this section summarises.
 
 ## Releases
 
@@ -169,10 +219,15 @@ directory, restart, then add the integration from **Settings → Devices & Servi
 ## Configuration
 
 1. Settings > Devices & Services > Add Integration > "NVIDIA Shield"
-2. Select the Android TV Remote entity for your Shield
-3. Enable ADB if you want now-playing from all apps
-4. If ADB is enabled, the next step will pair — approve the prompt on the Shield
-5. Optionally configure Jellyfin, receiver, power switch
+2. Give it a name and its address — the Shield's IP, pre-filled when discovery
+   found the device
+3. Both transports are on by default: **Read state over ADB** (now-playing from
+   every app) and **Add the Nvidia Remote Protocol** (power, availability, app
+   push, volume readout). Uncheck what you do not want.
+4. If ADB is enabled, the next step pairs it — approve the prompt on the Shield
+5. The remote protocol pairs next — type the PIN shown on the Shield, or
+   continue without pairing (that transport stays off until you pair it)
+6. Optionally configure Jellyfin, receiver, power switch
 
 ### ADB Pairing
 
@@ -189,7 +244,7 @@ service, and the discovered address is pre-filled on the setup form. The dedup
 rules are Home Assistant's own, and they differ with what the discovery carries:
 
 - **with** the device MAC, a duplicate aborts as "already configured", and an
-  existing entry's hosts are updated when the address changed;
+  existing entry's address is updated when it changed;
 - **without** a MAC, the flow follows HA's stricter
   `_async_handle_discovery_without_unique_id` contract: **any** existing entry
   for this integration aborts the discovery, and only one discovery flow runs at
@@ -205,7 +260,10 @@ helper the flow calls is a coroutine and its dedup only runs when awaited.
 - **Jellyfin Media Player** — auto-detected or manually selected
 - **Receiver + Input** — for media-zone coordination
 - **Power Switch** — smart plug entity
-- **ADB Host/Port** — override auto-detection if needed
+- **Read state over ADB / Add the Nvidia Remote Protocol** — turn either
+  transport on or off
+- **Shield address / ADB port** — the Shield's IP, and the ADB port if you
+  changed it from 5555
 
 ## Entities