chore: clean up AGENTS.md headings and remove stale flaky test note

Rename "Cursor Cloud specific instructions" to "Development instructions"
and remove outdated "Known flaky test" section.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: aidenybai

AGENTS.md

@@ -101,7 +101,7 @@ pnpm typecheck # runs type checking
 pnpm format
 ```
 
-## Cursor Cloud specific instructions
+## Development instructions
 
 This is a pnpm + Turborepo monorepo (19 packages under `packages/`). No external services (databases, Docker, etc.) are required.
 
@@ -117,10 +117,6 @@ The root `package.json` has `pnpm.onlyBuiltDependencies` configured for `@parcel
 
 E2E tests (`pnpm test` at root) run Playwright against the `e2e-playground` Vite dev server on port 5175 (auto-started by the Playwright config). Chromium must be installed: `npx --prefix packages/react-grab playwright install chromium --with-deps`.
 
-### Known flaky test
-
-`e2e/history-items.spec.ts` > "should reposition when toolbar is dragged to top edge" intermittently times out in headless CI environments. This is a pre-existing issue.
-
 ### Key commands reference
 
 See root `package.json` scripts and `CONTRIBUTING.md` for the full list. Quick reference: