chore: add extension icon + fix broken tile reference

config.json tile pointed at a non-existent chatelet.png. Add the shared aio
logo (static/image/aio.png) and point the tile at it — matches the fleet
convention (satmachineadmin/spirekeeper) and gives the catalog a valid icon.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019VUQCfdqiLSsFS2jcGnaFD

config.json

@@ -5,7 +5,7 @@
   "repo": "https://git.atitlan.io/aiolabs/chatelet",
   "short_description": "Nostr-native room rentals (Airbnb-style) for LNbits",
   "description": "",
-  "tile": "/chatelet/static/image/chatelet.png",
+  "tile": "/chatelet/static/image/aio.png",
   "min_lnbits_version": "1.4.0",
   "contributors": [
     {