Add Playwright web e2e scaffolding and OAuth test-mode overrides
Web app: add login_hint to PAR (spec-compliant), make handle
resolution and PLC directory URLs configurable via VITE_RESOLVE_API
and VITE_PLC_DIRECTORY_URL for test environments.
e2e-tests: add Playwright with global setup (fake-pds OAuth +
Vite dev server lifecycle), custom fixtures, and smoke tests.
Bump fake-pds to 0.3.0 for the new authorize endpoint. [CL-360]