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/pkg/crypto/batch_decrypt.go

@@ -1,76 +0,0 @@
-package crypto
-
-import (
-	"sync"
-)
-
-// BatchDecryptResult 批量解密结果
-type BatchDecryptResult struct {
-	Index     int
-	Plaintext []byte
-	Error     error
-}
-
-// BatchDecrypt 批量并行解密
-// workerCount 指定并行工作数，如果 <= 0 则使用 CPU 核数
-func (e *MessageEncryptor) BatchDecrypt(ciphertexts []string, workerCount int) [][]byte {
-	if e == nil || len(ciphertexts) == 0 {
-		return nil
-	}
-
-	results := make([][]byte, len(ciphertexts))
-
-	// 小批量直接串行处理
-	if len(ciphertexts) <= 10 {
-		for i, ct := range ciphertexts {
-			if ct == "" {
-				continue
-			}
-			plaintext, err := e.Decrypt(ct)
-			if err == nil {
-				results[i] = plaintext
-			}
-		}
-		return results
-	}
-
-	// 并行处理
-	jobs := make(chan int, len(ciphertexts))
-	var wg sync.WaitGroup
-
-	// 确定工作数
-	if workerCount <= 0 {
-		workerCount = 4 // 默认4个并行
-	}
-	if workerCount > len(ciphertexts) {
-		workerCount = len(ciphertexts)
-	}
-
-	// 启动 worker
-	for w := 0; w < workerCount; w++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
-			for i := range jobs {
-				ct := ciphertexts[i]
-				if ct == "" {
-					continue
-				}
-				plaintext, err := e.Decrypt(ct)
-				if err == nil {
-					results[i] = plaintext
-				}
-			}
-		}()
-	}
-
-	// 分发任务
-	for i := range ciphertexts {
-		jobs <- i
-	}
-	close(jobs)
-
-	wg.Wait()
-	return results
-}
-

internal/pkg/ws/hub.go

@@ -343,7 +343,7 @@ func (h *Hub) PublishToUserOnline(userID string, eventType string, payload any)
 }
 
 // PublishToUserOnlineReliable 可靠地发送事件给在线用户（阻塞发送）
-// 用于重要的信令消息（如 SDP, ICE candidate），确保消息送达
+// 用于重要的信令消息（如通话邀请、接听），确保消息送达
 // 如果用户不在线，返回 false
 func (h *Hub) PublishToUserOnlineReliable(userID string, eventType string, payload any) bool {
 	h.mu.RLock()