Fix CI change detection: save old HEAD before fetch/reset

The diff was comparing HEAD vs origin after fetch, but before the
first real push they point to the same commit — producing an empty
diff and skipping all builds. Now saves HEAD before fetch so the
comparison works, and falls back to rebuild-all when HEAD hasn't
moved (first deploy or CI re-run on same commit).

.gitea/workflows/ci.yml

@@ -34,18 +34,28 @@ jobs:
         run: |
           ssh "root@$DEPLOY_HOST" "
             cd ${{ env.COOP_DIR }}
-            git fetch origin ${{ github.ref_name }}
 
-            # Detect what changed since current HEAD
-            CHANGED=\$(git diff --name-only HEAD origin/${{ github.ref_name }})
+            # Save current HEAD before updating
+            OLD_HEAD=\$(git rev-parse HEAD 2>/dev/null || echo none)
+
+            git fetch origin ${{ github.ref_name }}
             git reset --hard origin/${{ github.ref_name }}
 
+            NEW_HEAD=\$(git rev-parse HEAD)
+
+            # Detect what changed
             REBUILD_ALL=false
-            if echo \"\$CHANGED\" | grep -q '^shared/'; then
-              REBUILD_ALL=true
-            fi
-            if echo \"\$CHANGED\" | grep -q '^docker-compose.yml'; then
+            if [ \"\$OLD_HEAD\" = \"none\" ] || [ \"\$OLD_HEAD\" = \"\$NEW_HEAD\" ]; then
+              # First deploy or CI re-run on same commit — rebuild all
               REBUILD_ALL=true
+            else
+              CHANGED=\$(git diff --name-only \$OLD_HEAD \$NEW_HEAD)
+              if echo \"\$CHANGED\" | grep -q '^shared/'; then
+                REBUILD_ALL=true
+              fi
+              if echo \"\$CHANGED\" | grep -q '^docker-compose.yml'; then
+                REBUILD_ALL=true
+              fi
             fi
 
             for app in blog market cart events federation account; do