chore(test-infra): install Playwright + axe-core; configure CT and e2e runners; enable Git LFS for screenshots

B1 of TEST-INFRA-001 (RFC-WS-FRONTEND-PRIMEVUE Amendment A-1).

- Add @playwright/test, @playwright/experimental-ct-vue,
  @axe-core/playwright as dev deps in apps/app
- Add @vue/compiler-dom (transitively required by ct-vue's Vite build
  pipeline; not auto-resolved on Vite 7)
- Install Chromium via `playwright install chromium` (host cache only,
  not committed)
- Configure Git LFS clean/smudge filters globally; track
  apps/app/tests/playwright-{ct,e2e}/__screenshots__/**/*.png
- Integrate `git lfs pre-push` into lefthook.yml since LFS's per-repo
  hook would conflict with the existing sync-staleness hook
- Add playwright/index.html + playwright/index.ts hook file with the
  full provider stack (Vuetify [TEMPORARY: replaced in F3 by PrimeVue],
  Pinia, TanStack Vue Query, memory-history Router with no auth
  guards)
- Add playwright.config.ts (e2e, Chromium-only, baseURL :5173, auto-
  starts `pnpm dev` via webServer)
- Add playwright-ct.config.ts (component testing, Linux-Chromium-only
  baselines, maxDiffPixelRatio 0.001, snapshot path template,
  ssr.noExternal: ['vuetify'] mirroring vitest.config.ts)
- Add scripts: test:component, test:e2e, test:visual,
  test:visual:update
- Add smoke test proving Chromium boots in the CT runner
- Update .gitignore for Playwright runtime artifacts (test-results/,
  playwright-report/, blob-report/, playwright/.cache/)

Vitest's existing 402 tests still pass unchanged.
DoD-17 / DoD-19 CI integration deferred to TEST-INFRA-002 per Amendment
A-1 scope cut (no CI exists in this repo today).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -39,6 +39,14 @@ storage/framework/views/*
 .phpunit.result.cache
 coverage/
 
+# Playwright runtime artifacts (test-results, blob-report, html-report,
+# .cache build dir, playwright traces). __screenshots__/ is committed
+# (via Git LFS, see .gitattributes).
+apps/app/test-results/
+apps/app/playwright-report/
+apps/app/blob-report/
+apps/app/playwright/.cache/
+
 # Misc
 *.pem
 .cache/