Add comprehensive security improvements across the application:
- **IP-based login protection**: Implement IP ban system tracking login failures, auto-banning after threshold exceeded
- **Ownership verification**: Add userID parameter to Delete/Update operations for posts and comments to prevent unauthorized modifications
- **SSRF protection**: Add URL and resolved host validation for image URLs in chat and OpenAI client
- **SQL injection prevention**: Add EscapeLikeWildcard utility to escape special characters in LIKE queries
- **HTTP security**: Configure server timeouts and add security headers middleware
- **Rate limiting**: Refactor to support configurable duration and per-endpoint rate limits for auth routes
- **Error handling**: Standardize error responses using HandleError and proper error types
- Remove BOM from all Go source files
- Standardize import ordering and whitespace across handlers and services
- Replace PostgreSQL full-text search with ILIKE pattern matching in post and user repositories
- Enhance JPush client with TLS transport, rate limit monitoring, and simplified API
- Refactor PushService to include userID in device management methods
- Add MaxDevicesPerUser limit and extract helper functions for push payload construction
Add complete trade functionality including:
- TradeItem, TradeImage, TradeFavorite models with auto-migration
- TradeRepository with CRUD and favorite operations
- TradeService with business logic for listing, creating, updating, status management
- TradeHandler with RESTful endpoints for trade operations
- DTOs and converters for request/response handling
Routes include: list, get by id, create, update, delete, status update, view recording, favorite/unfavorite.
