feat: migrate to DragonflyDB and clean up environment configuration

- Replace Redis with DragonflyDB for better performance and memory efficiency
- Remove redundant environment variables (POSTGRES_*, ENCRYPTION_KEY, OAUTH_SERVICE_URL)
- Consolidate database configuration to use single DB_* variables
- Use JWT_SECRET for both JWT tokens and encryption
- Remove PORT variable redundancy, use BACKEND_PORT consistently
- Clean up docker-compose configurations for dev/prod consistency
- Add DragonflyDB configuration with optimized memory usage
- Remove redis.conf as it's no longer needed
- Update health checks to use Redis-compatible CLI for DragonflyDB
- Add missing VITE_API_URL to production frontend
- Fix GitHub Actions to use correct go.sum path
- Clean up development directories and unused files

backend/internal/db/db.go

@@ -0,0 +1,87 @@
+package db
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+	"github.com/trackeep/backend/internal/db/sqlc"
+)
+
+// DB wraps the sqlc DB with additional functionality
+type DB struct {
+	*sqlc.Queries
+	pool *pgxpool.Pool
+}
+
+// NewDB creates a new database connection
+func NewDB() (*DB, error) {
+	// Get database connection string
+	dsn := fmt.Sprintf("host=%s user=%s password=%s dbname=%s port=%s sslmode=%s",
+		os.Getenv("DB_HOST"),
+		os.Getenv("DB_USER"),
+		os.Getenv("DB_PASSWORD"),
+		os.Getenv("DB_NAME"),
+		os.Getenv("DB_PORT"),
+		os.Getenv("DB_SSL_MODE"),
+	)
+
+	// Create connection pool
+	pool, err := pgxpool.New(context.Background(), dsn)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create connection pool: %w", err)
+	}
+
+	// Test connection
+	if err := pool.Ping(context.Background()); err != nil {
+		return nil, fmt.Errorf("failed to ping database: %w", err)
+	}
+
+	// Create queries instance
+	queries := sqlc.New(pool)
+
+	return &DB{
+		Queries: queries,
+		pool:    pool,
+	}, nil
+}
+
+// Close closes the database connection
+func (db *DB) Close() error {
+	db.pool.Close()
+	return nil
+}
+
+// BeginTx starts a transaction
+func (db *DB) BeginTx(ctx context.Context) (*DB, error) {
+	tx, err := db.pool.BeginTx(ctx, pgx.TxOptions{})
+	if err != nil {
+		return nil, err
+	}
+
+	return &DB{
+		Queries: sqlc.New(tx),
+		pool:    nil, // Not using pool in transaction mode
+	}, nil
+}
+
+// Commit commits the transaction
+func (db *DB) Commit() error {
+	// This would need to be implemented with transaction tracking
+	// For now, transactions should be handled by the caller
+	return nil
+}
+
+// Rollback rolls back the transaction
+func (db *DB) Rollback() error {
+	// This would need to be implemented with transaction tracking
+	// For now, transactions should be handled by the caller
+	return nil
+}
+
+// GetPool returns the underlying connection pool
+func (db *DB) GetPool() *pgxpool.Pool {
+	return db.pool
+}