fix(upload): detect unnamed multipart files

- Treat an existing multipart file field as upload content even when FileStorage has an empty filename.

- Keep upload telemetry aligned with file field presence instead of FileStorage truthiness.

- Add regression coverage for frontend-style uploads that provide a file field without a filename.

- Bump NanoShare to 1.27.2 and refresh the staged lockfile.

routes/side/upload.py

@@ -74,19 +74,21 @@ async def api_upload(user):
   text = form.get('text', '')
   orphan_registry = getattr(current_app, 'orphan_storage_registry', None)
 
-  add_wide_event_context(nanoshare={"operation": "upload", "has_file": bool(files.get('file')), "has_text": bool(text.strip())})
-
   uploaded = files.get('file')
+  has_uploaded_file = uploaded is not None
+
+  add_wide_event_context(nanoshare={"operation": "upload", "has_file": has_uploaded_file, "has_text": bool(text.strip())})
+
   expires_at_dt = ensure_utc(parse_expires(expires_raw))
 
-  if not uploaded and not text.strip():
+  if not has_uploaded_file and not text.strip():
     add_wide_event_context(nanoshare={"operation_status": "missing_content"})
     return jsonify({'ok': False, 'error': 'No content provided'}), 400
 
   content_type = None
 
   # --- binary upload path ---
-  if uploaded:
+  if has_uploaded_file:
     fname = uploaded.filename or ''
     add_wide_event_context(nanoshare={"upload_type": "file", "filename_present": bool(fname)})
     ctype = uploaded.mimetype or 'application/octet-stream'