Add full-feature device benchmarks and manual workflow

[Copilot]

Adds benchmark coverage for the app’s core IPTV flows: M3U/EPG/Xtream subscription, library browsing, playback entry, settings destinations, and TV remote-control subscription. Benchmark inputs can be driven from committed /testdata fixtures via GitHub raw URLs.

• Benchmark fixtures

  • Added /testdata M3U, EPG, and Xtream sample data.
  • Documented raw URL usage for manual/device benchmark runs.

• Device benchmark suite

  • Added a full-feature Mobly benchmark script with per-feature timing output.
  • Kept the existing remote-control TV subscription benchmark available as an alternate script.
  • Updated the Gradle benchmark task to run the full-feature suite by default.

• Debug benchmark wiring

  • Added debug-only settings keys to prefill M3U, EPG, and Xtream subscription forms.
  • Allows benchmark automation to exercise production UI paths without brittle text entry.

• Manual GitHub workflow

  • Added .github/workflows/device-benchmarks.yml.
  • Workflow is workflow_dispatch only.
  • Validates raw fixtures and benchmark scripts, compiles benchmark support modules, and can optionally run device benchmarks.

on:
  workflow_dispatch:
    inputs:
      run_device_benchmark:
        type: boolean
        default: false