tgbridge: shrink oversize gifs sent as files, not just as animations

A .gif uploaded as a document never matches the animation branch, so it
went to discord untouched and came back 413. First real test of the local
api server hit exactly this: a 27.2 MB gif fetched fine, then bounced.

Same ladder, same .gif out — that file lands at 5.73 MB.

Co-Authored-By: Claude Opus 5 <[email protected]>

tgbridge/forwarder.py

@@ -315,6 +315,14 @@ class TelegramForwarder:
 
         if document:
             data, filename = await self._download(document.file_id)
+            # a gif sent as a file never reaches the animation branch, so it
+            # went to discord at full size — same ladder, same .gif out
+            is_gif = (doc_mime == "image/gif"
+                      or filename.lower().endswith(".gif"))
+            if is_gif and len(data) > media.MAX_CONVERTED_BYTES:
+                smaller = await media.to_gif(data, ".gif")
+                if smaller:
+                    return [(filename, smaller)], ""
             return [(filename, data)], ""
 
         if message.voice: