feat(config_flow): standalone setup — androidtv entity optional with no_state_source validation, entry data omits the field for standalone entries, sensor tolerates its absence; migration keeps v1 field / v2 absence valid (P3-1a,d)

custom_components/nvidia_shield/strings.json

@@ -6,7 +6,7 @@
         "description": "Set up your NVIDIA Shield. Link the Android TV remote, Jellyfin, receiver, and power monitoring.",
         "data": {
           "name": "Device Name",
-          "androidtv_entity": "Android TV Remote",
+          "androidtv_entity": "The media_player entity from the Android TV Remote integration. Optional for standalone setups that pair with the Nvidia Remote Protocol instead.",
           "jellyfin_entity": "Jellyfin Media Player",
           "receiver_entity": "Receiver",
           "receiver_input": "Receiver Input",
@@ -53,7 +53,8 @@
       "adb_no_host": "Could not determine the Shield's IP address. Set the ADB Host field on the previous step.",
       "protocol_no_host": "Could not determine the Shield's IP address. Set the Protocol Host or ADB Host field.",
       "protocol_invalid_code": "Pairing has not started or the code is empty. Click Submit to retry.",
-      "protocol_pair_failed": "The Shield rejected that pairing code. Click Submit to try again."
+      "protocol_pair_failed": "The Shield rejected that pairing code. Click Submit to try again.",
+      "no_state_source": "No state source selected. Link the Android TV Remote entity or enable the Nvidia Remote Protocol pairing \u2014 the integration needs at least one source of power/app state."
     },
     "abort": {
       "already_configured": "This Shield entity is already configured.",
@@ -77,7 +78,7 @@
           "adb_port": "ADB Port"
         },
         "data_description": {
-          "jellyfin_entity": "The Jellyfin media_player for this device. Session stream info is read from the HA Jellyfin integration's existing coordinator — no extra config needed.",
+          "jellyfin_entity": "The Jellyfin media_player for this device. Session stream info is read from the HA Jellyfin integration's existing coordinator \u2014 no extra config needed.",
           "receiver_entity": "The receiver this device is connected to.",
           "receiver_input": "Which input on the receiver.",
           "power_entity": "Smart plug switch for reliable on/off detection.",