refactor: migrate app.config and Expo config plugins to TypeScript

Migrate the dynamic Expo config and all 12 local config plugins from
CommonJS .js to typed TypeScript:

- app.config.js -> app.config.ts (typed ConfigContext/ExpoConfig,
  behavior-identical port)
- plugins/*.js -> plugins/*.ts with `ConfigPlugin` typings from
  expo/config-plugins; plugin options are now type-checked (withGitPod)
- app.json plugin references updated to the .ts paths
- imports unified on expo/config-plugins (some plugins used the
  @expo/config-plugins alias)

Node evaluates the config at prebuild time and cannot parse TypeScript
plugin modules on its own (verified empirically: Expo transpiles
app.config.ts itself but not its imports), so the documented tsx
approach is used: `import "tsx/cjs"` at the top of app.config.ts plus
tsx as a devDependency.

Validation: resolved prebuild configs (expo config --type prebuild) are
byte-identical to the old JS config for both mobile and TV (modulo
plugin path extensions and the builtAt timestamp); full
`bun run prebuild` and `bun run prebuild:tv` pass and all Android
plugin mods are present in the generated project (media3 exclusions,
gradle properties, cast activity, network security config, alert
colors).

docs/tv-discovery.md

@@ -28,7 +28,7 @@ Apple TV uses a Top Shelf extension target, not the main app process.
 
 Relevant files:
 
-- [plugins/withTVOSTopShelf.js](../plugins/withTVOSTopShelf.js)
+- [plugins/withTVOSTopShelf.ts](../plugins/withTVOSTopShelf.ts)
 - [targets/StreamyfinTopShelf/TopShelfProvider.swift](../targets/StreamyfinTopShelf/TopShelfProvider.swift)
 - [modules/top-shelf-cache/ios/TopShelfCacheModule.swift](../modules/top-shelf-cache/ios/TopShelfCacheModule.swift)
 - [utils/topshelf/cache.ts](../utils/topshelf/cache.ts)