Testing: Add comprehensive E2E tests with Playwright

[Kami-no-san]

Description

Create E2E test suites using Playwright for critical user flows.

Files to Create

• apps/web/e2e/auth.spec.ts — login/register flows
• apps/web/e2e/projects.spec.ts — project CRUD flow
• apps/web/e2e/audits.spec.ts — audit creation and viewing
• apps/web/e2e/dashboard.spec.ts — dashboard navigation
• apps/web/playwright.config.ts — update if needed

Acceptance Criteria

• Auth flow: register → login → access dashboard → logout
• Projects flow: create project → view list → view detail → edit → delete
• Audits flow: create audit → view findings → update finding status → generate report
• Dashboard: verify navigation, stats, and responsive layout
• Tests run in CI (ci.yml)
• Tests use a seeded test database
• Screenshot on failure for debugging