fix(ci): use Docker bridge gateway IP 172.21.0.1:3300 for checkout

host.docker.internal not resolving in act containers on Synology Docker.
The gateway IP 172.21.0.1 routes to the host where Gitea is now
bound to 0.0.0.0:3300.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/deploy-claude-dev-dev.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Checkout repository
         run: |
           if [ ! -d .git ]; then
-            git clone --branch "${GITHUB_REF_NAME}" --depth=1 "http://host.docker.internal:3300/${GITHUB_REPOSITORY}.git" .
+            git clone --branch "${GITHUB_REF_NAME}" --depth=1 "http://172.21.0.1:3300/${GITHUB_REPOSITORY}.git" .
           fi
 
       - name: Resolve image tags