Replace in-memory database with Turso (libSQL)

[art049]

• Add Turso libSQL client dependency (github.com/tursodatabase/libsql-client-go)
• Add SQLite driver for local file support (github.com/mattn/go-sqlite3)
• Replace in-memory slice with libSQL database connection
• Support both local file and remote Turso database via environment variables
• Update all API handlers to use SQL queries instead of in-memory operations
• Maintain backward compatibility with existing API endpoints
• Database file: albums.db stores persistent album data locally

Environment variables:

• TURSO_DATABASE_URL: Database URL (defaults to file:./albums.db)
• TURSO_AUTH_TOKEN: Authentication token for remote Turso database (optional)

🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com

[codspeed-hq]

CodSpeed Performance Report

Merging #2 will degrade performances by 99.36%

_{Comparing feature/turso-integration (a87b887) with main (769218c)}

Summary

❌ 3 regressions
✅ 3 untouched

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	BenchmarkGetAlbumByIDExists	10.9 µs	1,581 µs	-99.31%
❌	BenchmarkGetAlbumByIDNotFound	10.1 µs	1,585.7 µs	-99.36%
❌	BenchmarkGetAlbums	15.7 µs	1,569.8 µs	-99%