Add chat_action parameter to send_telegram_notification service

Shows typing/upload indicator while processing media. Supports:
typing, upload_photo, upload_video, upload_document actions.
Set to empty string to disable. Default: typing.

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

custom_components/immich_album_watcher/translations/en.json

@@ -244,6 +244,10 @@
                 "send_large_photos_as_documents": {
                     "name": "Send Large Photos As Documents",
                     "description": "How to handle photos exceeding Telegram's limits (10MB or 10000px dimension sum). If true, send as documents. If false, downsize to fit limits."
+                },
+                "chat_action": {
+                    "name": "Chat Action",
+                    "description": "Chat action to display while processing (typing, upload_photo, upload_video, upload_document). Set to empty to disable."
                 }
             }
         }