docs: correct two stale claims about a tier and a red proof (t44 0b/0c)

media_player.py's module docstring still described the command path as
"protocol key push → ADB keyevent → external androidtv_remote", calling the last
tier "transitional; removed in Phase 4". t41 removed it, so the sentence
documented a path that no longer exists; it now names the two real tiers.

tests/test_module_coverage.py recorded the sweeps' red proof as the pre-t41 commit.
That commit cannot prove either sweep: at c588a7c ``helpers.py`` still DEFINED
``discover_adb_host`` (line 45, and button.py imported it successfully), so there
was no broken relative import to find — and that commit's ``ha_api_drift.py``
predates BOTH passes (no entity-contract check, no package-import check), so a
real-HA run there is clean: verified just now, exit 0, "no Home-Assistant API
drift (13 modules, 60 imports, 35 call arguments, 7 awaited HA calls)". The
docstring now says the proof is built rather than borrowed, which is what the two
red-proof tests actually do (a copy of the tree with the reference reverted).

Verified: 362 passed / 2 skipped, ruff clean.

custom_components/nvidia_shield/media_player.py

@@ -9,8 +9,9 @@ State architecture:
   - Power ladder: protocol is_on push → ADB wake (exact mWakefulness) → plug off
   - Playback state: Jellyfin (polling, slow 10-30s) or ADB media session
   - Metadata: Jellyfin attributes
-  - Commands: protocol key push → ADB keyevent → external androidtv_remote
-    (the last tier is transitional; removed in Phase 4)
+  - Commands: protocol key push → ADB keyevent. The external androidtv_remote
+    entity tier that used to back this is gone — t41 removed it with the entity,
+    so there is no third command path to keep in step.
 
 Intent tracking bridges the gap between instant commands and slow Jellyfin polling:
   1. User presses pause → intent recorded → UI shows paused immediately