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

@@ -4,12 +4,6 @@ on:
   push:
   workflow_dispatch:
 
-# Only one run per branch at a time. A new push cancels any in-progress run,
-# preventing duplicate builds when the runner picks up the same event twice.
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: true
-
 permissions:
   contents: write   # required for creating releases
   packages: write
@@ -186,13 +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 ───────────────────────────────────────────────
+          # ── 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() {