Add full-text song search endpoint

[Akatenvictor]

What

Add a song search endpoint with full-text search across title, artist name, and tags with relevance ranking.

Why

Users need to find specific songs quickly. A robust search capability improves the user experience and content discoverability on the platform.

Scope

• In: Full-text search endpoint, relevance scoring, search suggestion prefix
• Out: Advanced filters, search history, typo tolerance, fuzzy matching

Acceptance Criteria

• GET /api/search?q=query returns ranked results
• Searches across song title, artist name, album name
• Results include song metadata and artist info
• Relevance scoring based on match quality
• Pagination support for large result sets
• Minimum query length of 2 characters
• Response time under 200ms for typical queries

Technical Context

• SongService in src/services/SongService for search logic
• SongController in src/controllers/ for search handler
• SongRoutes in src/routes/SongRoutes for route
• Consider using database full-text search or LIKE with indexed columns
• CacheService for caching frequent search results