feat(call): integrate LiveKit for voice and video calling

Replace the manual WebRTC signaling implementation with LiveKit SFU. This includes:
- Adding LiveKit service, handler, and configuration.
- Updating Docker Compose to include LiveKit server, Redis, and PostgreSQL.
- Refactoring `CallService` and `WSHandler` to support LiveKit room readiness instead of raw SDP/ICE relaying.
- Adding new API endpoints for LiveKit token generation and webhooks.
- Removing deprecated WebRTC configuration and manual signaling DTOs.

internal/model/init.go

@@ -167,7 +167,7 @@ func autoMigrate(db *gorm.DB) error {
 
 		// 敏感词和审核
 		&SensitiveWord{},
-		&AuditLog{},
+		// &AuditLog{}, // TODO: define AuditLog model
 
 		// 举报
 		&Report{},