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/src/i18n/index.ts

@@ -4,33 +4,21 @@ import type { SupportedLocale } from './messages'
 
 const saved = localStorage.getItem('hermes_locale')
 
+function normalize(tag: string): SupportedLocale {
+  return tag.toLowerCase().startsWith('zh') ? 'zh' : 'en'
+}
+
 function resolveLocale(saved: string | null): SupportedLocale {
   if (saved && (supportedLocales as readonly string[]).includes(saved)) {
     return saved as SupportedLocale
   }
 
-  function normalize(tag: string): SupportedLocale | null {
-    const lower = tag.toLowerCase()
-    if (lower.startsWith('zh')) {
-      const isTraditional =
-        lower.includes('hant') ||
-        lower.includes('-tw') ||
-        lower.includes('-hk') ||
-        lower.includes('-mo')
-      return isTraditional ? 'zh-TW' : 'zh'
-    }
-    const short = tag.slice(0, 2)
-    if ((supportedLocales as readonly string[]).includes(tag)) return tag as SupportedLocale
-    if ((supportedLocales as readonly string[]).includes(short)) return short as SupportedLocale
-    return null
-  }
+  // A locale stored before the zh/en-only consolidation (for example 'zh-TW'
+  // or 'ja') is no longer supported; remap it instead of dropping to English.
+  if (saved) return normalize(saved)
 
-  for (const lang of navigator.languages) {
-    const resolved = normalize(lang)
-    if (resolved) return resolved
-  }
-
-  return 'en'
+  const preferred = navigator.languages[0]
+  return preferred ? normalize(preferred) : 'en'
 }
 
 function setHtmlLang(locale: SupportedLocale) {