Add drag-and-drop image upload & quarantine

Add support for uploading images via drag-and-drop and bulk form uploads and handle unreadable images by quarantining them. Backend: new endpoints for single and bulk uploads (/api/local/sessions/{id}/images/upload and /bulk-upload), session notifications endpoint, CacheStore.delete_dataset_manifest_images, upload helpers (sanitize, temp write, chunked reads), quarantine/move-to-not_valid logic, InvalidSessionImageError, and integration into fingerprint warmup/duplicate search flows. Frontend: drag-and-drop overlay, handlers, batching, upload progress UI, new API types and upload functions, notification polling, and updates to deletion flow to use summary responses. Also add CSS for the drop overlay and add python-multipart to requirements for multipart uploads.

Author: SunOner

backend/app/cache_store.py

@@ -511,6 +511,53 @@ def save_dataset_manifest(
                     (dataset_key, dataset_key),
                 )
 
+    def delete_dataset_manifest_images(
+        self,
+        root_path: Path,
+        image_ids: Sequence[str],
+        relative_paths: Sequence[str],
+        image_count: int,
+    ):
+        dataset_key = self.dataset_key_for_path(root_path)
+        unique_image_ids = list(dict.fromkeys(image_ids))
+        unique_relative_paths = list(dict.fromkeys(relative_paths))
+        now = time.time()
+
+        if not unique_image_ids and not unique_relative_paths:
+            return
+
+        with self._lock:
+            with self._connect() as connection:
+                if unique_relative_paths:
+                    connection.executemany(
+                        """
+                        DELETE FROM dataset_images
+                        WHERE dataset_key = ? AND relative_path = ?
+                        """,
+                        [
+                            (dataset_key, relative_path)
+                            for relative_path in unique_relative_paths
+                        ],
+                    )
+
+                if unique_image_ids:
+                    connection.executemany(
+                        """
+                        DELETE FROM image_fingerprints
+                        WHERE dataset_key = ? AND image_id = ?
+                        """,
+                        [(dataset_key, image_id) for image_id in unique_image_ids],
+                    )
+
+                connection.execute(
+                    """
+                    UPDATE dataset_manifests
+                    SET image_count = ?, updated_at = ?
+                    WHERE dataset_key = ?
+                    """,
+                    (image_count, now, dataset_key),
+                )
+
     def update_dataset_annotation_metadata(
         self,
         root_path: Path,