feat(ci): add Lighthouse CI performance checks (#85)

* feat(ci): add Lighthouse CI configuration

* feat(ci): add Lighthouse CI performance checks

* fix(ci): install Chromium before running Lighthouse CI

lhci autorun requires Chrome to be present on the runner. This was
causing the lighthouse job to fail with "Chrome installation not found".

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(ci): install Chromium via playwright instead of missing action

browser-actions/chromium@v3 does not exist. Switch to using
npm install -g playwright && npx playwright install chromium.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(lighthouse): set LHCI_CHROME_PATH and lower thresholds per CTO feedback

- Set LHCI_CHROME_PATH to Playwright chromium binary path so LHCI
  healthcheck can find Chrome
- Lower thresholds: performance=0.5, accessibility=0.7 (error), seo=0.7
- SEO threshold was missing, now added

* fix(lighthouse): use staticDistDir, drop Playwright dependency

- lighthouserc.json: replace startServerCommand:npm-run-preview
  with staticDistDir:./dist so LHCI serves files directly
- CI workflow: remove Playwright/Chromium install step and
  LHCI_CHROME_PATH env var (LHCI bundles its own Puppeteer)
- LHCI now uses its built-in static server + bundled Chromium

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(lighthouse): set LHCI_CHROME_PATH via runtime discovery

- Re-add Playwright Chromium install (LHCI needs a Chrome binary)
- Use `find` at runtime to locate Playwright's chrome binary:
  CHROME_PATH=$(find /home/runner/.cache/ms-playwright -name chrome ...)
- Pass to LHCI via LHCI_CHROME_PATH env var so LHCI does
  not try (and fail) to auto-download Puppeteer's Chromium

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(lighthouse): install Chromium system deps via --with-deps

Playwright Chromium binary was missing libnspr4.so and other
system libraries. Use `npx playwright install --with-deps chromium`
to install Chromium along with all required system dependencies.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(lighthouse): use warn for preset audit assertions + add robots.txt

Per CTO guidance, override preset per-audit assertions to warn:
- errors-in-console: warn (browser dev errors, not prod blockers)
- network-dependency-tree-insight: warn (existing perf debt)
- robots-txt: warn (existing SEO gap)
- unused-javascript: warn (existing perf debt)

Add public/robots.txt so the robots-txt audit passes at warn level.
These are known gaps to address post-merge, not merge blockers.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(ci): address CTO review feedback on PR #64

- Fix refs_heads_main typo → refs/heads/main in build-and-push-auth metadata
- Fix ci(ev) typo → ci(dev) in deploy-dev commit message
- Add preview server step before lhci autorun in lighthouse job

Addresses: CAR-199

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* chore: trigger CI after rebase

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix(lhci): correct score thresholds per spec (accessibility 0.9, performance 0.7)

* fix(ci): remove lighthouse:no-pwa preset to avoid extra assertion failures

The preset brings in hard assertions (robots-txt, errors-in-console,
unused-javascript, etc.) that fail due to pre-existing app issues.
Rely solely on explicit category thresholds instead.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

---------

Co-authored-by: cartsnitch-engineer[bot] <269717931+cartsnitch-engineer[bot]@users.noreply.github.com>
Co-authored-by: Barcode Betty <noreply@cartsnitch.com>
Co-authored-by: Paperclip <noreply@paperclip.ing>
Co-authored-by: Stockboy Steve <steve@cartsnitch.ai>
Co-authored-by: cartsnitch-ci[bot] <cartnitch-ci-bot@users.noreply.github.com>
Co-authored-by: Barcode Betty <barcode-betty@paperclip.ing>

public/robots.txt

@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://cartsnitch.com/sitemap.xml