refactor: extract db migrations from main to internal/database

internal/database/migrate.go

@@ -0,0 +1,57 @@
+package database
+
+import (
+	"database/sql"
+	"log"
+	"os"
+)
+
+func RunMigrations(db *sql.DB) error {
+	// Create migration tracking table
+	_, err := db.Exec(`
+		CREATE TABLE IF NOT EXISTS migration_version (
+			name TEXT PRIMARY KEY,
+			applied_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
+		)
+	`)
+	if err != nil {
+		return err
+	}
+
+	migrations := []string{
+		"migrations/001_init.sql",
+		"migrations/002_add_anime_titles.sql",
+	}
+
+	for _, migrationFile := range migrations {
+		// Check if migration already applied
+		var exists int
+		err := db.QueryRow("SELECT COUNT(*) FROM migration_version WHERE name = ?", migrationFile).Scan(&exists)
+		if err != nil {
+			return err
+		}
+		if exists > 0 {
+			log.Printf("migration %s already applied, skipping", migrationFile)
+			continue
+		}
+
+		// Read and execute migration
+		migrationSQL, err := os.ReadFile(migrationFile)
+		if err != nil {
+			return err
+		}
+		if _, err := db.Exec(string(migrationSQL)); err != nil {
+			return err
+		}
+
+		// Mark as applied
+		_, err = db.Exec("INSERT INTO migration_version (name) VALUES (?)", migrationFile)
+		if err != nil {
+			return err
+		}
+
+		log.Printf("migration %s applied successfully", migrationFile)
+	}
+
+	return nil
+}