Add visual-tests job to CI

Runs Vitest browser visual regression tests (drawElevationChart) on every
PR and push to main. Uses the same Playwright/Chromium cache as the e2e job.

On first run (no committed snapshots yet) the tests create the snapshots and
pass. On subsequent runs they compare against committed snapshots and fail on
visual regression. Failed runs upload a visual-snapshots-diff artifact so the
diff is visible in the Actions UI.

To update snapshots after an intentional visual change:
  Actions → "Update visual snapshots" → Run workflow (or add the
  `update-snapshots` label to the PR).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -110,6 +110,44 @@ jobs:
       - run: pnpm install --frozen-lockfile
       - run: pnpm build
 
+  visual-tests:
+    name: Visual Tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+
+      - name: Cache Playwright browsers
+        id: playwright-cache
+        uses: actions/cache@v5
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-${{ hashFiles('pnpm-lock.yaml') }}
+
+      - name: Install Playwright Chromium
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
+        run: pnpm exec playwright install --with-deps chromium
+
+      - name: Install Playwright deps only
+        if: steps.playwright-cache.outputs.cache-hit == 'true'
+        run: pnpm exec playwright install-deps chromium
+
+      - name: Run visual regression tests
+        run: pnpm --filter @trails-cool/planner test:visual
+
+      - name: Upload screenshots on failure
+        if: failure()
+        uses: actions/upload-artifact@v7
+        with:
+          name: visual-snapshots-diff
+          path: apps/planner/app/**/__screenshots__/
+          retention-days: 7
+
   e2e:
     name: E2E Tests
     needs: build