chore: add type definitions for react-textfit

Installed @types/react-textfit to resolve TypeScript compilation error
in PlayingGuideModal.tsx. This package provides type definitions for
the react-textfit library used in the Rithmomachia guide component.

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

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

apps/web/package.json

@@ -94,6 +94,7 @@
     "@types/node": "^20.0.0",
     "@types/react": "^18.2.0",
     "@types/react-dom": "^18.2.0",
+    "@types/react-textfit": "^1.1.4",
     "@types/ws": "^8.18.1",
     "@vitejs/plugin-react": "^5.0.2",
     "concurrently": "^8.0.0",