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/service/message_segment_image.go

@@ -10,7 +10,7 @@ import (
 )
 
 // ValidateChatMessageImageSegments 校验聊天消息中的图片段：禁止 data:/base64 内联，仅允许引用本站 S3 公开前缀下的 URL。
-func (s *UploadService) ValidateChatMessageImageSegments(segments model.MessageSegments) error {
+func (s *uploadService) ValidateChatMessageImageSegments(segments model.MessageSegments) error {
 	if s == nil || s.s3Client == nil {
 		return nil
 	}