Native InnerTube player extraction, scrub preview and fullscreen gesture pass

[A-EDev]

Summary

• The video player resolves every load through the native InnerTube client — player screen, service-layer queue advance and watch metadata — replacing the second extraction stack on this path.
• New scrub preview on the seek bar: a sliding filmstrip or a single frame, selected in Player Appearance, with the time, chapter and SponsorBlock segment labelled while scrubbing.
• Most-replayed heatmap drawn above the seek bar with its peak badged, and chapters read from the watch response.
• Frame-by-frame stepping while paused, behind a settings toggle that defaults off.
• Fullscreen gesture pass: the system back-gesture edges no longer trigger seek, volume or brightness; the read-outs are centred; the transport row scales its spacing to the player width; the top read-outs clear the display cutout in portrait fullscreen.
• The volume and brightness overlay style is picked from a sheet that previews each option.
• Captions translate into the preferred language on every load path.

Related issue

Closes #1068
Closes #1057
Follows up on #1029

Change type

• Bug fix
• Feature
• Refactor or maintenance
• Build, packaging, or CI
• Documentation

Validation

• ./gradlew :app:assembleGithubDebug
• ./gradlew :app:testGithubDebugUnitTest — 2003 tests, 0 failures
• I ran any additional flavor-specific build or test tasks affected by this change. — :app:compileFossDebugKotlin, spotlessCheck
• I manually tested the affected behavior on an Android device or emulator.

Test device and Android version: Poco X6 Pro, Android 16, HyperOS 3.0.9.0

Screenshots or recordings

To attach: scrub filmstrip and preview box, the rewatch heatmap, and the portrait-fullscreen top read-outs.

Risk and compatibility

• The change does not introduce secrets, private data, or unexpected telemetry.
• New user-facing text uses Android string resources.
• Dependency and lockfile changes are intentional and limited to this PR.
• Room schema changes include the required version bump and migration, or this PR does not change the Room schema.
• Breaking changes and upgrade steps are clearly documented.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.