Add skill for testing timesheet-app end to end

[devin-ai-integration]

Adds .agents/skills/testing-timesheet-app/SKILL.md, written while running an end-to-end verification of the app.

It documents:

• booting both servers (backend npm start on :3001, frontend npm run dev on :5173 with Vite proxying /api)
• passwordless/email-only auth and lazy user provisioning
• exact validation limits (hours 0.01-24 inclusive, description <=1000 chars)
• CSV/PDF export locations and formats, including the known epoch-value Date column in exports
• the correct coverage invocation npm run test:coverage (npm test coverage is not a script)

Devin Session: https://partner-workshops.devinenterprise.com/sessions/7eed8c66f3e848beb07f367c67ad2085

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud