ci: remove broken concurrency block, make release step idempotent

- Removed concurrency/cancel-in-progress: on this Gitea runner version
  cancelled runs get re-queued causing an infinite restart loop
- Release creation now checks for existing tag first (GET releases/tags/TAG)
  and reuses the existing release ID if found, preventing the second
  duplicate run from failing with a 409/422 tag-already-exists error

.gitea/workflows/android-build.yml

@@ -94,11 +94,21 @@ jobs:
 
       - name: Build Debug APK
         working-directory: android
-        run: ./gradlew assembleDebug --no-daemon
+        run: |
+          # Retry up to 3 times to survive transient network errors when the
+          # Gradle wrapper downloads its distribution from GitHub CDN.
+          for attempt in 1 2 3; do
+            ./gradlew assembleDebug --no-daemon && break
+            [ "$attempt" -lt 3 ] && echo "Attempt $attempt failed — retrying in 30s..." && sleep 30 || exit 1
+          done
 
       - name: Build Release APK (unsigned — no signing key required)
         working-directory: android
-        run: ./gradlew assembleRelease --no-daemon
+        run: |
+          for attempt in 1 2 3; do
+            ./gradlew assembleRelease --no-daemon && break
+            [ "$attempt" -lt 3 ] && echo "Attempt $attempt failed — retrying in 30s..." && sleep 30 || exit 1
+          done
 
       # ── 9. Upload APKs as workflow artifacts ─────────────────────────────────
       - name: Upload APKs as artifacts
@@ -170,13 +180,20 @@ jobs:
           MD_LIST=$(echo "$COMMIT_LOG" | sed 's/^/- /')
           BODY=$(printf '%s' "$MD_LIST" | python3 -c "import sys,json; print(json.dumps(sys.stdin.read()))")
 
-          # ── Create the release ───────────────────────────────────────────────
-          RESP=$(curl -sf -X POST "$API/releases" \
-            -H "Authorization: token $TOKEN" \
-            -H "Content-Type: application/json" \
-            -d "{\"tag_name\":\"$TAG\",\"name\":\"Build $VERSION\",\"body\":$BODY,\"draft\":false,\"prerelease\":false}")
-          RELEASE_ID=$(echo "$RESP" | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
-          echo "Created release $TAG (id=$RELEASE_ID)"
+          # ── Create release (idempotent: reuse existing tag if already present) ───
+          EXISTING=$(curl -sf "$API/releases/tags/$TAG" \
+            -H "Authorization: token $TOKEN" || true)
+          if [[ -n "$EXISTING" ]]; then
+            RELEASE_ID=$(echo "$EXISTING" | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
+            echo "Release $TAG already exists (id=$RELEASE_ID) — reusing."
+          else
+            RESP=$(curl -sf -X POST "$API/releases" \
+              -H "Authorization: token $TOKEN" \
+              -H "Content-Type: application/json" \
+              -d "{\"tag_name\":\"$TAG\",\"name\":\"Build $VERSION\",\"body\":$BODY,\"draft\":false,\"prerelease\":false}")
+            RELEASE_ID=$(echo "$RESP" | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
+            echo "Created release $TAG (id=$RELEASE_ID)"
+          fi
 
           # ── Upload APKs as release assets ────────────────────────────────────
           upload_asset() {