Implemented lyrics button on player to fetch and display song lyrics

[Wikijito7]

Solves #110

📋 Changelist Summary

Added a lyrics button (📝) to the player that fetches and displays song lyrics using LavaLyrics + LavaSrc (Deezer + LrcLib), with auto-follow on track changes and toggle on/off behavior.

💬 Description

• Created LyricsService wrapping LavaLyrics' LyricsManager with registerLyricsManager(), loadLyrics(), and getFormattedLyrics()
• Registered Deezer AudioSourceManager and LrcLibLyricsManager as lyrics providers in AudioPlayerManagerProvider
• Added PLAYER_LYRICS component and 📝 button to the player action row
• Implemented toggle behavior in PlayerCommand.onInteract(): first click sends public lyrics + auto-follows track changes, second click deletes it
• Added lyricsMessage field in GuildLavaPlayerService with updateLyricsMessage() in onTrackStart() and cleanup on disconnect
• Added localization keys (EN/ES) for all user-facing strings
• Updated CommandHandlerService routing for PLAYER_LYRICS
• 12 new unit tests: 5 for LyricsService, 5 for PlayerCommand.handleLyricsButton(), 1 for AudioPlayerManagerProvider (lyricsConfigured), 1 for CommandHandlerService (routing)

ℹ️ Extra info

• All 355 tests pass (5 pre-existing skipped)
• Lyrics resolution priority: Deezer (native) → LrcLib (fallback for any track)
• Error messages (no track, no lyrics) are ephemeral — only the clicker sees them
• Coverage improvements: CommandHandlerServiceTest (0%→4.5%), PlayerCommandTest (6.7%→10.0%), AudioPlayerManagerProviderTest (83.3%→87.5%)

[sonarqubecloud]

Quality Gate failed

Failed conditions
C Security Rating on New Code (required ≥ A)

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