feat(web): restyle hero preview badge and grow wide-sidebar settings icon

The hero Preview tag becomes a superscript mono pill riding the title's
top-right (r24, bordered, business-tertiary fill), colored by the new
--dsw-alias-label-primary-bluish alias over --dsw-static-blue-900 — the
first design-owner-approved addition under the token-sheet authority
exception recorded in the ui-theme README. The expanded sidebar trigger
now uses the native 16px settings icon instead of the 14px asset.

packages/client/ui-theme/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/client/ui-theme/README.md
-README.md: 88e21fe214ec806b101050949690283d811be36d
-README.zh.md: ba781ba89a62292928a7b05ab94ea1cd930b4f50
+README.md: 648213b258169b2e8869a93d058fcc65aece175e
+README.zh.md: b807ebd66253c91dc8b79f01ac4d3b2335682001