fix: skip test-action for PRs created by claude bot

When Claude creates a PR (e.g. upstream-sync), the pull_request event
fires with actor=claude. The self-trigger guard in actor.ts blocks
this because actor 'claude' matches bot_name 'claude[bot]', causing
test-action to fail with "Blocking self-trigger" error.

Add `if: github.actor != 'claude'` to the test-agent-mode job.
Claude-created PRs (upstream syncs) don't need the integration test
since they're merge commits, not action code changes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.forgejo/workflows/test-action.yml

@@ -23,6 +23,7 @@ jobs:
   test-agent-mode:
     name: Test Agent Mode on Forgejo
     runs-on: grunt
+    if: github.actor != 'claude'
     steps:
     - name: Checkout
       uses: https://${{ secrets.READ_REPO_TOKEN }}@git.wxs.ro/xternal/checkout@v6.0.2