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/config/logger.go

@@ -0,0 +1,84 @@
+package config
+
+import (
+	"os"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+var Logger *zap.Logger
+
+// InitLogger initializes the Zap logger
+func InitLogger() {
+	// Get log level from environment
+	logLevel := os.Getenv("LOG_LEVEL")
+	if logLevel == "" {
+		logLevel = "info"
+	}
+
+	// Parse log level
+	var level zapcore.Level
+	switch logLevel {
+	case "debug":
+		level = zapcore.DebugLevel
+	case "info":
+		level = zapcore.InfoLevel
+	case "warn":
+		level = zapcore.WarnLevel
+	case "error":
+		level = zapcore.ErrorLevel
+	default:
+		level = zapcore.InfoLevel
+	}
+
+	// Check if we're in production mode
+	isProduction := os.Getenv("GIN_MODE") == "release"
+
+	// Configure encoder
+	var encoder zapcore.Encoder
+	encoderConfig := zap.NewProductionEncoderConfig()
+	encoderConfig.TimeKey = "timestamp"
+	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder
+
+	if isProduction {
+		encoder = zapcore.NewJSONEncoder(encoderConfig)
+	} else {
+		encoder = zapcore.NewConsoleEncoder(encoderConfig)
+	}
+
+	// Configure output
+	writeSyncer := zapcore.AddSync(os.Stdout)
+
+	// Create core
+	core := zapcore.NewCore(encoder, writeSyncer, level)
+
+	// Create logger
+	Logger = zap.New(core, zap.AddCaller(), zap.AddStacktrace(zapcore.ErrorLevel))
+
+	// Replace global logger
+	zap.ReplaceGlobals(Logger)
+
+	Logger.Info("Logger initialized",
+		zap.String("level", logLevel),
+		zap.Bool("production", isProduction),
+	)
+}
+
+// GetLogger returns the configured logger instance
+func GetLogger() *zap.Logger {
+	if Logger == nil {
+		// Fallback to default logger if not initialized
+		logger, _ := zap.NewProduction()
+		return logger
+	}
+	return Logger
+}
+
+// SyncLogger flushes any buffered log entries
+func SyncLogger() {
+	if Logger != nil {
+		_ = Logger.Sync()
+	}
+}