feat: implement Redis-based message bus and awareness management

- Added RedisMessageBus for message distribution using Redis Pub/Sub.
- Introduced LocalMessageBus as a no-op implementation for single-server mode.
- Created messagebus interface for abstraction of message distribution.
- Implemented awareness management methods: SetAwareness, GetAllAwareness, DeleteAwareness, and ClearAllAwareness.
- Added logger utility for structured logging with zap.
- Refactored SniffYjsClientIDs and MakeYjsDeleteMessage functions for improved readability.

backend/internal/logger/logger.go

@@ -0,0 +1,41 @@
+package logger
+
+import (
+	"os"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// NewLogger creates a production-grade logger with appropriate configuration
+func NewLogger(isDevelopment bool) (*zap.Logger, error) {
+	var config zap.Config
+
+	if isDevelopment {
+		config = zap.NewDevelopmentConfig()
+		config.EncoderConfig.EncodeLevel = zapcore.CapitalColorLevelEncoder
+	} else {
+		config = zap.NewProductionConfig()
+		config.EncoderConfig.TimeKey = "timestamp"
+		config.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	}
+
+	// Allow DEBUG level in development
+	if isDevelopment {
+		config.Level = zap.NewAtomicLevelAt(zapcore.DebugLevel)
+	}
+
+	logger, err := config.Build()
+	if err != nil {
+		return nil, err
+	}
+
+	return logger, nil
+}
+
+// NewLoggerFromEnv creates logger based on environment
+func NewLoggerFromEnv() (*zap.Logger, error) {
+	env := os.Getenv("ENVIRONMENT")
+	isDev := env == "" || env == "development" || env == "dev"
+	return NewLogger(isDev)
+}