docs: improve Mock gotcha wording in CLAUDE.md

Umi auto-discovers mock file changes in most cases. Update the wording
to reflect this rather than implying a restart is always needed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CLAUDE.md

@@ -154,7 +154,7 @@ The CLI also supports MCP server mode: `npx antd mcp` (for IDE integrations).
 
 - **`.umi` directory**: Auto-generated by Umi. If dev server behaves unexpectedly, delete `src/.umi` and restart
 - **Port 8000 in use**: Kill the process (`lsof -ti:8000 | xargs kill`) or use `PORT=3000 npm start` to change it
-- **Mock not updating**: Restart dev server after adding new mock files; Umi discovers mocks on startup only
+- **Mock not updating**: Umi usually auto-discovers `mock/` and `src/pages/**/_mock.ts` changes. If a new file isn't recognized, try restarting the dev server
 - **Biome + antd lint**: Both must pass before committing. `npm run lint` runs Biome + tsc; `npx antd lint ./src` runs separately. Do not install ESLint or Prettier — this project uses Biome only
 - **`src/services/` is auto-generated**: Never edit manually. Run `npm run openapi` to regenerate
 - **`npm run simple` is irreversible**: Always commit or branch before running it