fix: add success/media fields to MediaUploadResponse schema

- Add success and media fields to MediaUploadResponse
- Add url alias field to MediaItemResponse for JS compatibility
- JS expects response.success and response.media.url

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/schema/media.py

@@ -37,6 +37,7 @@ class MediaItemResponse(BaseModel):
     filename: str
     original_filename: str | None = None
     file_url: str
+    url: str | None = None  # Alias for file_url for JS compatibility
     thumbnail_url: str | None = None
     media_type: str  # image, video, document
     mime_type: str | None = None
@@ -52,6 +53,11 @@ class MediaItemResponse(BaseModel):
 
     model_config = {"from_attributes": True}
 
+    def model_post_init(self, __context: Any) -> None:
+        """Set url from file_url if not provided."""
+        if self.url is None:
+            object.__setattr__(self, "url", self.file_url)
+
 
 class MediaListResponse(BaseModel):
     """Paginated list of media items."""
@@ -71,13 +77,16 @@ class MediaListResponse(BaseModel):
 class MediaUploadResponse(BaseModel):
     """Response for single file upload."""
 
+    success: bool = True
+    message: str | None = None
+    media: MediaItemResponse | None = None
+    # Legacy fields for backwards compatibility
     id: int | None = None
     file_url: str | None = None
     thumbnail_url: str | None = None
     filename: str | None = None
     file_size: int | None = None
     media_type: str | None = None
-    message: str | None = None
 
 
 class UploadedFileInfo(BaseModel):