feat: enhance security with IP banning, ownership checks, and SSRF protection

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

internal/service/sticker_service.go

@@ -1,7 +1,6 @@
 package service
 
 import (
-	"errors"
 	"net/url"
 	"strings"
 
@@ -119,7 +118,7 @@ func (s *stickerService) DeleteSticker(userID string, stickerID string) error {
 		return err
 	}
 	if sticker.UserID != userID {
-		return errors.New("sticker not found")
+		return apperrors.ErrForbidden
 	}
 
 	return s.stickerRepo.Delete(stickerID)