chore(docs): run visual regression in CI; align DatePicker text color

- Add `Visual regression tests` step to CI, following the Playwright install
  introduced for the accessibility suite.
- Switch DatePicker weekday header and dim/disabled cell text to
  `--ty-color-text-secondary` (with the previous `--ty-*-color-muted` token as
  fallback) so the picker uses the same secondary-text token as the rest of
  the library.
- Loosen visual regression tolerance from `maxDiffPixels: 100` to
  `maxDiffPixelRatio: 0.03` so subpixel anti-aliasing differences across
  rendering passes don't flake the suite.
- Refresh recorded screenshots to match the new DatePicker color and the
  Button demo titles ("Type" → "Variant", "More Types" → "Semantic Colors").

Author: wangdicoder

.changeset/date-picker-secondary-text.md

@@ -0,0 +1,5 @@
+---
+'@tiny-design/react': patch
+---
+
+Switch DatePicker's muted/dim cell text and weekday header color from `--ty-picker-input-color-muted` / `--ty-date-picker-cell-color-muted` to `--ty-color-text-secondary` (with the previous token kept as a fallback). Brings the date picker in line with the shared secondary-text token used across the rest of the library.

.github/workflows/ci.yml

@@ -47,6 +47,9 @@ jobs:
       - name: Accessibility tests
         run: pnpm test:accessibility
 
+      - name: Visual regression tests
+        run: pnpm test:visual
+
       - name: Upload Playwright report
         if: failure()
         uses: actions/upload-artifact@v4

apps/docs/playwright.config.ts

@@ -10,7 +10,7 @@ export default defineConfig({
   reporter: process.env.CI ? [['html'], ['list']] : 'list',
   expect: {
     toHaveScreenshot: {
-      maxDiffPixels: 100,
+      maxDiffPixelRatio: 0.03,
     },
   },
   webServer: {