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/handler/call_handler.go

@@ -49,12 +49,3 @@ func (h *CallHandler) GetCallHistory(c *gin.Context) {
 		"page":  page,
 	})
 }
-
-// GetICEServers 获取 ICE 服务器配置
-// GET /api/v1/calls/ice-servers
-func (h *CallHandler) GetICEServers(c *gin.Context) {
-	servers := h.callService.GetICEServers()
-	response.Success(c, gin.H{
-		"ice_servers": servers,
-	})
-}