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/public/manifest.webmanifest

@@ -1,7 +1,7 @@
 {
-  "name": "Hermes Studio",
-  "short_name": "Hermes",
-  "description": "Self-hosted AI chat dashboard for Hermes Agent",
+  "name": "hermes-ui",
+  "short_name": "hermes-ui",
+  "description": "Self-hosted web dashboard for Hermes Agent",
   "start_url": "/#/hermes/chat",
   "scope": "/",
   "display": "standalone",