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/ws_handler.go

@@ -212,7 +212,7 @@ func (h *WSHandler) readPump(conn *websocket.Conn, client *ws.Client) {
 		conn.Close()
 	}()
 
-	conn.SetReadLimit(256 * 1024) // 256KB (SDP/ICE candidates can be large)
+	conn.SetReadLimit(256 * 1024) // 256KB
 	conn.SetReadDeadline(time.Now().Add(60 * time.Second))
 	conn.SetPongHandler(func(string) error {
 		zap.L().Debug("WebSocket pong received",
@@ -383,10 +383,8 @@ func (h *WSHandler) handleMessage(client *ws.Client, msg *ws.Message) {
 		h.handleCallReject(ctx, client, msg.Payload)
 	case "call_busy":
 		h.handleCallBusy(ctx, client, msg.Payload)
-	case "call_sdp":
-		h.handleCallSDP(ctx, client, msg.Payload)
-	case "call_ice":
-		h.handleCallICE(ctx, client, msg.Payload)
+	case "call_ready":
+		h.handleCallReady(ctx, client, msg.Payload)
 	case "call_end":
 		h.handleCallEnd(ctx, client, msg.Payload)
 	case "call_mute":
@@ -717,43 +715,18 @@ func (h *WSHandler) handleCallBusy(ctx context.Context, client *ws.Client, paylo
 	}
 }
 
-// handleCallSDP 转发 SDP
-func (h *WSHandler) handleCallSDP(ctx context.Context, client *ws.Client, payload json.RawMessage) {
+// handleCallReady 处理通话就绪（LiveKit 房间连接成功）
+func (h *WSHandler) handleCallReady(ctx context.Context, client *ws.Client, payload json.RawMessage) {
 	var req struct {
-		CallID  string          `json:"call_id"`
-		SDPType string          `json:"sdp_type"`
-		SDP     json.RawMessage `json:"sdp"`
-	}
-	if err := json.Unmarshal(payload, &req); err != nil || req.CallID == "" || req.SDPType == "" {
-		h.publisher.SendError(client, "invalid_params", "call_id and sdp_type are required")
-		return
-	}
-
-	signalPayload, _ := json.Marshal(map[string]any{
-		"sdp_type": req.SDPType,
-		"sdp":      json.RawMessage(req.SDP),
-	})
-	if err := h.callService.RelaySignal(ctx, req.CallID, client.UserID, "call_sdp", signalPayload); err != nil {
-		h.publisher.SendError(client, "call_sdp_failed", err.Error())
-	}
-}
-
-// handleCallICE 转发 ICE candidate
-func (h *WSHandler) handleCallICE(ctx context.Context, client *ws.Client, payload json.RawMessage) {
-	var req struct {
-		CallID    string          `json:"call_id"`
-		Candidate json.RawMessage `json:"candidate"`
+		CallID string `json:"call_id"`
 	}
 	if err := json.Unmarshal(payload, &req); err != nil || req.CallID == "" {
 		h.publisher.SendError(client, "invalid_params", "call_id is required")
 		return
 	}
 
-	signalPayload, _ := json.Marshal(map[string]any{
-		"candidate": json.RawMessage(req.Candidate),
-	})
-	if err := h.callService.RelaySignal(ctx, req.CallID, client.UserID, "call_ice", signalPayload); err != nil {
-		h.publisher.SendError(client, "call_ice_failed", err.Error())
+	if err := h.callService.Ready(ctx, req.CallID, client.UserID); err != nil {
+		h.publisher.SendError(client, "call_ready_failed", err.Error())
 	}
 }