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/wire/infrastructure.go

@@ -1,11 +1,12 @@
-package wire
+package wire
 
 import (
+	"fmt"
 	"time"
 
 	"with_you/internal/cache"
 	"with_you/internal/config"
-	"with_you/internal/model"
+	"with_you/internal/database"
 	"with_you/internal/pkg/crypto"
 	"with_you/internal/pkg/email"
 	"with_you/internal/pkg/hook"
@@ -18,8 +19,8 @@ import (
 	"with_you/internal/repository"
 	"with_you/internal/service"
 
-	redisPkg "github.com/redis/go-redis/v9"
 	"github.com/google/wire"
+	redisPkg "github.com/redis/go-redis/v9"
 	"go.uber.org/zap"
 	"gorm.io/gorm"
 )
@@ -74,7 +75,7 @@ func ProvideConfig() (*config.Config, error) {
 
 // ProvideDB 提供数据库连接
 func ProvideDB(cfg *config.Config) (*gorm.DB, error) {
-	return model.NewDB(&cfg.Database)
+	return database.NewDB(&cfg.Database)
 }
 
 // ProvideRedisClient 提供 Redis 客户端
@@ -145,7 +146,7 @@ func ProvideBuiltinHooks(manager *hook.Manager) *hook.BuiltinHooks {
 // ProvideModerationHooks 注册审核钩子
 func ProvideModerationHooks(
 	manager *hook.Manager,
-	postAIService *service.PostAIService,
+	postAIService service.PostAIService,
 	postRepo repository.PostRepository,
 	commentRepo repository.CommentRepository,
 	userRepo repository.UserRepository,
@@ -248,6 +249,7 @@ func ProvideTransactionManager(db *gorm.DB) repository.TransactionManager {
 }
 
 // ProvideMessageEncryptor 提供消息加密器
+// 加密启用时密钥必须是 32 字节（AES-256），否则视为致命配置错误，启动期 fail-fast。
 func ProvideMessageEncryptor(cfg *config.Config) error {
 	if !cfg.Encryption.Enabled {
 		zap.L().Info("Message encryption is disabled")
@@ -255,15 +257,12 @@ func ProvideMessageEncryptor(cfg *config.Config) error {
 	}
 
 	if len(cfg.Encryption.Key) != 32 {
-		zap.L().Error("Encryption key must be 32 bytes for AES-256",
-			zap.Int("actual_length", len(cfg.Encryption.Key)),
-		)
-		return nil
+		// 致命安全配置：不允许降级为「加密已启用但实际不加密」
+		return fmt.Errorf("encryption is enabled but key must be 32 bytes for AES-256, got %d", len(cfg.Encryption.Key))
 	}
 
 	if err := crypto.InitMessageEncryptor(cfg.Encryption.Key, cfg.Encryption.KeyVersion); err != nil {
-		zap.L().Error("Failed to initialize message encryptor", zap.Error(err))
-		return err
+		return fmt.Errorf("failed to initialize message encryptor: %w", err)
 	}
 
 	zap.L().Info("Message encryption initialized successfully",