serve assets and the store archive from gitea-watch (the GitHub repo is gone)

github.com/Worph/MetaAppStore answers 404, and with it every jsDelivr
cdn.jsdelivr.net/gh/Worph/MetaAppStore@main/ URL: the icons, thumbnails and
screenshots of all 44 apps were missing from the store listing, and the store
source in the README no longer downloaded.

- Asset URLs in every Apps/*/docker-compose.yml now point at
  https://gitea-watch.nsl.sh/metastar/MetaAppStore/raw/branch/main/Apps/{AppName}/
  (103 of the 109 distinct URLs checked: 200 image/png). The other 6, MetaGateway
  and MetaWatch screenshot-1..3, name files that have never been in this repo.
- README: the store source is https://gitea-watch.nsl.sh/metastar/MetaAppStore/archive/main.zip
  (public, checked to download anonymously).
- CLAUDE.md and CONTRIBUTING.md: the asset rule and its grep guard follow, so an
  import cannot bring back a jsDelivr URL unnoticed.

Apps/MetaGatewayShared/docker-compose.yml

@@ -130,7 +130,7 @@ services:
       retries: 10
       start_period: 5s
     labels:
-      icon: https://cdn.jsdelivr.net/gh/Worph/MetaAppStore@main/Apps/MetaGateway/icon.png
+      icon: https://gitea-watch.nsl.sh/metastar/MetaAppStore/raw/branch/main/Apps/MetaGateway/icon.png
     networks:
       - metagateway
       - pcs
@@ -166,7 +166,7 @@ services:
       retries: 10
       start_period: 5s
     labels:
-      icon: https://cdn.jsdelivr.net/gh/Worph/MetaAppStore@main/Apps/MetaGateway/icon.png
+      icon: https://gitea-watch.nsl.sh/metastar/MetaAppStore/raw/branch/main/Apps/MetaGateway/icon.png
     networks:
       - metagateway
 
@@ -256,7 +256,7 @@ services:
       caddy_2.3_handle: ""
       caddy_2.3_handle.reverse_proxy: "{{upstreams 80}}"
 
-      icon: https://cdn.jsdelivr.net/gh/Worph/MetaAppStore@main/Apps/MetaGateway/icon.png
+      icon: https://gitea-watch.nsl.sh/metastar/MetaAppStore/raw/branch/main/Apps/MetaGateway/icon.png
     networks:
       - metagateway
       - pcs
@@ -277,7 +277,7 @@ x-casaos:
   category: Media
   developer: Aptero Team
   hostname: metagateway-${APP_DOMAIN}
-  icon: https://cdn.jsdelivr.net/gh/Worph/MetaAppStore@main/Apps/MetaGateway/icon.png
+  icon: https://gitea-watch.nsl.sh/metastar/MetaAppStore/raw/branch/main/Apps/MetaGateway/icon.png
   index: /
   is_uncontrolled: false
   main: metagateway