Add settings persistance on backend

backend/internal/db/migrations.go

@@ -0,0 +1,73 @@
+package db
+
+import (
+	"fmt"
+	"log"
+)
+
+type Migration struct {
+	Version int
+	SQL     string
+}
+
+var migrations = []Migration{
+	{
+		Version: 1,
+		SQL: `CREATE TABLE IF NOT EXISTS settings (
+			user_id INTEGER PRIMARY KEY,
+			settings TEXT
+		)`,
+	},
+	// Add new migrations here as your schema evolves
+}
+
+func (db *DB) Migrate() error {
+	// Create migrations table if it doesn't exist
+	_, err := db.Exec(`CREATE TABLE IF NOT EXISTS migrations (
+		version INTEGER PRIMARY KEY
+	)`)
+	if err != nil {
+		return err
+	}
+
+	// Get current version
+	var currentVersion int
+	err = db.QueryRow("SELECT COALESCE(MAX(version), 0) FROM migrations").Scan(&currentVersion)
+	if err != nil {
+		return err
+	}
+
+	// Apply new migrations
+	for _, migration := range migrations {
+		if migration.Version > currentVersion {
+			log.Printf("Applying migration %d", migration.Version)
+
+			tx, err := db.Begin()
+			if err != nil {
+				return err
+			}
+
+			_, err = tx.Exec(migration.SQL)
+			if err != nil {
+				tx.Rollback()
+				return fmt.Errorf("migration %d failed: %v", migration.Version, err)
+			}
+
+			_, err = tx.Exec("INSERT INTO migrations (version) VALUES (?)", migration.Version)
+			if err != nil {
+				tx.Rollback()
+				return fmt.Errorf("failed to update migration version: %v", err)
+			}
+
+			err = tx.Commit()
+			if err != nil {
+				return fmt.Errorf("failed to commit migration %d: %v", migration.Version, err)
+			}
+
+			currentVersion = migration.Version
+		}
+	}
+
+	log.Printf("Database is at version %d", currentVersion)
+	return nil
+}