Phase 002: rebrand to hermes-ui and consolidate i18n to zh/en

Removes the ekko / hermes-web-ui branding from the whole tree and drops
eight locale files, so the project presents one name and one language pair.

Data compatibility is deliberate, not accidental: DB filenames, the JWT
audience, and skill manifest ownership all still recognise their pre-rename
values so existing deployments under ~/.hermes-web-ui keep working without a
re-login or a re-injection.

scripts/harness-check.mjs now scans for the legacy strings and fails the
build on any new occurrence, with an explicit allow-list (and reasons) for
the compatibility paths that must keep them.

packages/client/index.html

@@ -8,9 +8,9 @@
   <link rel="manifest" href="/manifest.webmanifest" />
   <meta name="theme-color" content="#f7f7f4" />
   <meta name="apple-mobile-web-app-capable" content="yes" />
-  <meta name="apple-mobile-web-app-title" content="Hermes Studio" />
+  <meta name="apple-mobile-web-app-title" content="hermes-ui" />
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-  <title>Hermes Studio</title>
+  <title>hermes-ui</title>
   <style>
     html,
     body,