feat: add Lunabeat lyrics source and remove NetEase

[Zennmn]

Summary

• Add Lunabeat TTML Hub import to standalone and embedded lyrics settings.
• Cache manifest and songs index with ETag/304 and revision refresh; use a dedicated 2 MiB index limit and exact Apple Music ID matching.
• Skip the known inconsistent manifest.indexSha256, while retaining per-TTML size, structure, and SHA-256 validation.
• Remove NetEase EAPI/YRC conversion code, UI entries, tests, and documentation; preserve removed-provider entries as manual TTML mappings.
• Tolerate Lunabeat catalog entries without Apple Music IDs so unrelated records do not invalidate the full index.

Validation

• :app:testDebugUnitTest
• :app:lintDebug
• :app:lintVitalRelease
• :app:assembleRelease
• git diff main...HEAD --check

This branch is based directly on main and intentionally does not include the CJK changes from PR #49.

[Zennmn]

@codex

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Default automatic lookups to off for existing installs

When upgrading an installation that already has custom_lyrics_enabled=true, the new key is absent and this default silently enables playback-time requests to AMLL, Lunabeat, and AM-Lyrics. Those users previously opted into an offline/manual replacement feature, so merely upgrading now sends each eligible song ID to external services without enabling the new “自动实时补全” switch; default the missing key to false or add an explicit migration/consent step.

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