refactor(server): decouple services and improve architecture

- Introduce interfaces for all major services (JWT, PostAI, Comment, Message, Notification, QRCodeLogin, Upload, Vote, etc.) to support dependency inversion.
- Move query parameters from `internal/dto` to a new `internal/query` package to separate request payloads from data transfer objects.
- Refactor `internal/router` to use embedded `RouterDeps` for cleaner dependency management.
- Decouple handlers from repositories by injecting services instead of direct repository access, ensuring proper layering.
- Improve database initialization by moving it from `internal/model` to `internal/database`.
- Optimize message decryption by implementing a more efficient `BatchDecrypt` method in `MessageEncryptor` using a worker pool.
- Enhance error handling and security by implementing fail-fast checks for encryption key length during startup.
- Clean up unused code, including the `avatar` package and several unused DTOs.

internal/pkg/crypto/message_encryptor.go

@@ -139,31 +139,70 @@ func (e *MessageEncryptor) GetKeyVersion() int {
 	return e.keyVersion
 }
 
-// RotateKey 密钥轮换（用于密钥升级）
-// 新密钥必须也是32字节
-func (e *MessageEncryptor) RotateKey(newKey string, newVersion int) error {
-	keyBytes := []byte(newKey)
-	if len(keyBytes) != 32 {
-		return ErrInvalidKey
+// BatchDecrypt 批量解密多条密文，返回与输入等长的明文字节切片数组。
+// 并发度由 workers 指定（<=0 时按密文数量自适应）。
+// 解密失败或空密文的位置返回 nil，调用方可据此判断。
+// 这是 Decrypt 的无锁读优化版：AEAD 的 Open 不修改内部状态，
+// 但仍走 RLock 以兼容未来可能的密钥轮换语义。
+func (e *MessageEncryptor) BatchDecrypt(ciphertexts []string, workers int) [][]byte {
+	results := make([][]byte, len(ciphertexts))
+	if e == nil || len(ciphertexts) == 0 {
+		return results
 	}
 
-	block, err := aes.NewCipher(keyBytes)
-	if err != nil {
-		return err
+	// 自适应并发度：与历史实现保持一致
+	if workers <= 0 {
+		switch {
+		case len(ciphertexts) < 20:
+			workers = 2
+		case len(ciphertexts) > 100:
+			workers = 8
+		default:
+			workers = 4
+		}
+	}
+	if workers > len(ciphertexts) {
+		workers = len(ciphertexts)
 	}
 
-	gcm, err := cipher.NewGCM(block)
-	if err != nil {
-		return err
+	// 预取一次 AEAD，避免 worker 内重复进入 RLock
+	e.mu.RLock()
+	gcm := e.gcm
+	nonceSize := e.gcm.NonceSize()
+	e.mu.RUnlock()
+
+	jobs := make(chan int, len(ciphertexts))
+	var wg sync.WaitGroup
+
+	for w := 0; w < workers; w++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for i := range jobs {
+				ct := ciphertexts[i]
+				if ct == "" {
+					continue
+				}
+				raw, err := base64.StdEncoding.DecodeString(ct)
+				if err != nil || len(raw) < nonceSize {
+					continue
+				}
+				nonce := raw[:nonceSize]
+				actual := raw[nonceSize:]
+				plaintext, err := gcm.Open(nil, nonce, actual, nil)
+				if err != nil {
+					continue
+				}
+				results[i] = plaintext
+			}
+		}()
 	}
 
-	e.mu.Lock()
-	defer e.mu.Unlock()
+	for i := range ciphertexts {
+		jobs <- i
+	}
+	close(jobs)
+	wg.Wait()
 
-	e.key = keyBytes
-	e.gcm = gcm
-	e.keyVersion = newVersion
-
-	return nil
+	return results
 }
-