feat: add cross-browser extension with AI reading assistant

- Create Pi Reader browser extension for Chrome/Firefox
- Chrome uses Side Panel API, Firefox uses Sidebar Action API
- Supports both browsers with separate manifests and unified codebase
- Built with mini-lit components and Tailwind CSS v4
- Features model selection dialog with Ollama support
- Hot reload development server watches both browser builds
- Add useDefineForClassFields: false to fix LitElement reactivity

tsconfig.json

@@ -9,5 +9,6 @@
 			"@mariozechner/pi": ["./packages/pods/src/index.ts"]
 		}
 	},
-	"include": ["packages/*/src/**/*", "packages/*/test/**/*"]
+	"include": ["packages/*/src/**/*", "packages/*/test/**/*"],
+	"exclude": ["packages/browser-extension/**/*"]
 }