LyricsPlus & BetterLyrics providers, provider order, embedded-lyrics detection, batch UI overhaul

[DynamycSound]

Implements issues #4, #5 and #6, plus two batch-download UI improvements.

Issue #4 — LyricsPlus & BetterLyrics providers (word-by-word / TTML)

• LyricsPlus (LyricsPlusAPI): queries /v2/lyrics/get across the 6 community mirrors from the issue, remembering the last working one. "Word" responses are converted into the app's enhanced-LRC dialect ([mm:ss.SSS] line stamps + <begin>word <end> inline timing, same shape as the Apple/QQ output), with v1:/v2: voice tags and [bg:...] background blocks in multi-person mode. "Line" responses become regular synced LRC.
• BetterLyrics (BetterLyricsAPI): fetches Apple-style TTML from lyrics-api.boidu.dev and converts it via a new pure-Kotlin TtmlLyricsParser (word spans, syllable merging, ttm:agent voices, x-bg background vocals; translation/romanization spans skipped).
• Both are direct-fetch providers (no search offsets), so the smart matcher got a dedicated searchDirect path: a hit may only auto-accept when the local duration was sent along (the service verified the length); otherwise it's capped at REVIEW. They also work as the selected provider in the single-song and quick-search flows.

Issue #5 — embedded lyrics not detected on the home page

• New EmbeddedLyrics reader: reads the LYRICS/USLT tag via TagLib, memoised per file on (lastModified, length) so the full-library rescan on every Home resume stays cheap.
• LrcPrescan gained an injectable embedded-lyrics fallback (new EMBEDDED_SYNCED / EMBEDDED_UNSYNCED results): a track with embedded synced lyrics now shows under "Has lyrics", and an embedded synced body outranks a plain sidecar .lrc.
• The batch "skip songs with existing lyrics" check honours embedded synced lyrics too, and embedding lyrics from the app invalidates the cache entry.

Issue #6 — provider fallback chain in user-defined order

• New Provider order section in Settings: reorder providers with arrows, untick to skip one. Persisted robustly (unknown names dropped, newly added providers appended).
• The batch engine and the single-song search now walk exactly that chain, one provider at a time, until a match is found (the old adaptive "hot provider" reshuffling is gone so behaviour always matches what Settings shows). "Try every provider" off = only the first provider of the chain.

Batch download UI

• The batch options popup is replaced by a full-screen setup page (nav destination like the progress screen) with the song count, all options as settings rows and a bottom Start button. Back from the progress screen returns straight to Home.
• The Synced / Unsynced / Not found / Failed counters on the progress screen are now tappable: each opens a bottom drawer that rests at half the screen and can be dragged up to full height, listing the affected songs (album art, artist, provider). Tapping a song with lyrics opens the existing lyrics preview sheet.

Tests

• New JVM tests: TtmlLyricsParserTest (parsing, syllable merging, LRC output, time formats), EmbeddedLyricsPrescanTest (embedded fallback precedence), ProviderOrderParsingTest (persistence round-trip).
• testDebugUnitTest: 70 tests, all green except the pre-existing SuicideboysMatchTest, which queries the live LRCLib API and fails in this sandboxed environment independent of this diff.

Closes #4, closes #5, closes #6.

🤖 Generated with Claude Code

https://claude.ai/code/session_012b5krdonsAyKdwbAjhFxP8

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