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/sqlc/db.go

@@ -0,0 +1,32 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.30.0
+
+package sqlc
+
+import (
+	"context"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
+)
+
+type DBTX interface {
+	Exec(context.Context, string, ...interface{}) (pgconn.CommandTag, error)
+	Query(context.Context, string, ...interface{}) (pgx.Rows, error)
+	QueryRow(context.Context, string, ...interface{}) pgx.Row
+}
+
+func New(db DBTX) *Queries {
+	return &Queries{db: db}
+}
+
+type Queries struct {
+	db DBTX
+}
+
+func (q *Queries) WithTx(tx pgx.Tx) *Queries {
+	return &Queries{
+		db: tx,
+	}
+}