Expose AppFunctions for TMDB search and watchlist mutations

[odaridavid]

Summary

• Adds an Android 16+ AppFunctions surface so Gemini / Routines can search TMDB and mutate the on-device watchlist without opening the app.
• Five functions: searchMovies, searchTvShows, listWatchlist, addToWatchlist, removeFromWatchlist. addToWatchlist is idempotent (it checks the current list before delegating to ToggleWatchlistUseCase, which would otherwise remove an existing entry).
• All functions are wired to existing common use cases via Koin; KMP shape is preserved (only androidMain knows about AppFunctions).

Changes

• gradle/libs.versions.toml: android-compileSdk 36→37; add androidx.appfunctions 1.0.0-alpha02 + three aliases.
• composeApp/build.gradle.kts: deps on androidx.appfunctions{,-service}, kspAndroid compiler, ksp { arg("appfunctions:aggregateAppFunctions", "true") }.
• composeApp/src/androidMain/res/xml/app_metadata.xml: capability + operational-pattern description for agents.
• AndroidManifest.xml: <property android:name="android.app.appfunctions.app_metadata" .../>.
• appfunctions/SmoovieAppFunctions.kt (new): five @AppFunction methods + SmoovieTitle / SmoovieSearchPage @AppFunctionSerializable types with inline KDoc per property.
• PlatformModule.android.kt: Koin single for SmoovieAppFunctions.
• SmoovieApplication: implements AppFunctionConfiguration.Provider, resolves the class via KoinPlatform.getKoin().

Notes

• For alpha02: @AppFunction / AppFunctionConfiguration live under androidx.appfunctions.service, and isDescribedByKDoc = true (referenced in the official docs) was removed — KDoc is now always parsed.
• MediaType is exposed as a String ("movie" / "tv") to match TMDB conventions and stay within @AppFunctionSerializable-supported types.
• AGP 8.13.2 prints a non-fatal "tested up to compile SDK 36.1" warning against compileSdk = 37. Suppressible via android.suppressUnsupportedCompileSdk=37.0 in gradle.properties if noisy.

Test plan

• ./gradlew :composeApp:compileDebugKotlinAndroid (green locally)
• ./gradlew :composeApp:compileCommonMainKotlinMetadata + compileKotlinIosSimulatorArm64 (KMP didn't regress; green locally)
• ./gradlew :composeApp:ktlintCheck (green locally)
• Install debug build on an Android 16+ device with App Check debug token registered
• adb shell cmd app_function list-app-functions | grep dev.odaridavid.smoovie — confirm all five functions register
• adb shell cmd app_function execute-app-function --package dev.odaridavid.smoovie --function "<searchMovies id>" --parameters '{"query":"Dune","page":1}' — returns titles
• Repeat for addToWatchlist with a tmdbId from the search; open the Watchlist tab — entry should appear
• Repeat invocation of addToWatchlist with same tmdbId — no duplicate (idempotency)
• removeFromWatchlist — entry disappears from the Watchlist tab
• If on Android 17 with Gemini AppFunctions enabled: try a natural-language voice command like "add Dune Part Two to my Smoovie watchlist" — confirm the right function is matched

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