i18n(player): resolve PlayerViewModel messages in the composable

[ReichiMD]

What

Same approach as #632/#634, applied to the player's view-model messages — this
time following the pattern you added yourself in 4691412 (PluginMessage +
localizedText()), because these strings are built outside a composable.

PlayerViewModel assembled its own user-facing text: the loading phases, the
playback errors, the AI-translation toast and every "Find best match" status and
result. A view model only holds the application context, whose resources follow
the system language rather than the language selected in the app, so those
messages ignored the in-app language — the six context.getString(...) calls in
that file did, and the 34 remaining string literals could not be moved at all
without hitting the same problem.

• messages now travel through PlayerUiState as PlayerMessage (a @param:StringRes
  id plus its format arguments) and PlayerScreen resolves them
• 31 new keys added to values/strings.xml in the player section, with German
  values in values-de/strings.xml
• the 6 context.getString(...) calls in the view model are gone (0 left)
• nested messages are supported, so the reference-source label ("Built-in" /
  "Hearing") inside a match status is localized too
• one extra PlayerMessage.Raw case carries a platform exception message, which
  has no resource — this keeps the existing behaviour of that one error path exactly

Why

Approved in Discord (28 Aug): "Yes try to also bring hardcoded things into this.
That has been kinda a long time bug. They dont have to be in English yea."

This benefits all 50 language folders, not just German — untranslated locales fall
back to English exactly as before.

Notes

• Rendered English text is unchanged, character for character. Where a message had
  an optional suffix (" (auto-offset +2.0s)", " (best 87%)"), it became a second
  full-sentence resource instead of a concatenation, so translators get whole
  sentences and word order can differ per language.
• reportPlaybackError now records the stable resource entry name
  (player_fail_render_failed) in telemetry instead of the displayed sentence, so
  error reports stay comparable across languages.
• Stored and compared values are untouched: subtitle/audio preference values, the
  "Built-in" / "Hearing" label used in the SubMatch log line, and the
  language names all stay English. Log and telemetry strings are out of scope.
• No layout or behaviour change — the same messages appear in the same places, now
  in the app's language. Happy to add screenshots if useful.
• Verified by ./gradlew testSideloadDebugUnitTest in CI (compile + unit tests green).

created by Claude (Anthropic) on behalf of @ReichiMD