ci: stop running test-android on main (self-hosted runner offline)

The test-android job runs on ubuntu-self-hosted, which is currently
offline. On pushes to main the job sits in `queued` indefinitely, so the
Check run never completes and main can never report green. Gate the job
to PRs labeled `Android 🤖` only (matching the test-macos pattern),
removing it from main pushes.

Temporary; re-enabling on main is tracked in #379.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UCN2h9xbyn4yhxfVZyMzAm

Author: kraenhansen

.github/workflows/check.yml

@@ -234,7 +234,11 @@ jobs:
         env:
           MOCHA_REMOTE_CONTEXT: allTests
   test-android:
-    if: github.ref == 'refs/heads/main' || contains(github.event.pull_request.labels.*.name, 'Android 🤖')
+    # Temporarily gated to labeled PRs only: the ubuntu-self-hosted runner is
+    # offline, so running this on main pushes leaves the job queued forever and
+    # blocks the whole Check run from completing. Re-enable on main once the
+    # self-hosted runner is back. Tracked in #379.
+    if: contains(github.event.pull_request.labels.*.name, 'Android 🤖')
     name: Test app (Android)
     runs-on: ubuntu-self-hosted
     steps: