refactor: upgrade ESLint 9→10 and simplify React lint toolchain

- Upgrade eslint and @eslint/js to v10
- Replace eslint-plugin-react-x + eslint-plugin-react-dom + eslint-plugin-react-hooks
  with unified @eslint-react/eslint-plugin
- Raise dev Node.js requirement to ^22.13.0 || >=24 (runtime packages unaffected)
- Add .npmrc with engine-strict=true
- Move all @eslint-react rule overrides to eslint.config.js,
  eliminating plugin-specific inline eslint-disable comments
- Fix real issues caught by new rules: useless assignments,
  leaked setTimeout, ref naming, useState setter naming

packages/extension/src/agent/RemotePageController.ts

@@ -56,7 +56,7 @@ export class RemotePageController {
 	}
 
 	async getBrowserState(): Promise<BrowserState> {
-		let browserState = {} as BrowserState
+		let browserState: BrowserState
 		debug('getBrowserState', this.currentTabId)
 
 		const currentUrl = await this.getCurrentUrl()