Restore correct favicon from git history

Previous commit restored wrong favicon (from ui-extensions-dev-console).
This commit restores the actual original favicon.ico that was deleted
from packages/app/assets/graphiql/favicon.ico in commit b27ac4a.

Original size: 11,957 bytes (was incorrectly restored as 15,086 bytes)

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: amcaplan