chore: add broker demo video, exclude .runner from git

- product/site/squaremcp-broker-demo.mp4 — 45s mortgage broker demo video
  served at squaremcp.com/squaremcp-broker-demo.mp4, sent to Ferrari Lending
- .gitignore: add .runner (Gitea Actions runner token, should not be committed)

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

.gitignore

@@ -13,6 +13,7 @@ README.private.md
 hermes.log
 .claude/
 .codex
+.runner
 opencode.json
 
 # Remotion demo project