feat: add Playwright E2E testing infrastructure #62
Description
Summary
Add reusable Playwright E2E testing infrastructure to enable automated browser-based testing of module UI behavior.
Motivation
- Unit tests cover business logic but not UI behavior
- Manual browser testing burns through Claude context quickly
- Need repeatable, CI-friendly UI verification
Scope
Infrastructure (reusable):
- Playwright config and dependencies
- Login fixture with session reuse
- Page objects for common pages (Admin Globals, module menu)
- Compose override pattern for different test configurations
- Taskfile commands for running E2E tests
Out of scope:
- Feature-specific test cases (those go in feature PRs)
- Full integration tests requiring external services (Sinch, webhooks)
Acceptance Criteria
- Playwright installed and configured
- Login fixture works against local Docker environment
- At least one smoke test demonstrating the pattern
- Documentation for adding new E2E tests