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.

tests/client/pwa-metadata.test.ts

@@ -7,13 +7,13 @@ describe('PWA metadata', () => {
 
     expect(html).toContain('rel="manifest" href="/manifest.webmanifest"')
     expect(html).toContain('rel="apple-touch-icon" href="/logo.png"')
-    expect(html).toContain('name="apple-mobile-web-app-title" content="Hermes Studio"')
+    expect(html).toContain('name="apple-mobile-web-app-title" content="hermes-ui"')
   })
 
   it('ships a standalone web manifest with the Hermes icon', () => {
     const manifest = JSON.parse(readFileSync('packages/client/public/manifest.webmanifest', 'utf8'))
 
-    expect(manifest.name).toBe('Hermes Studio')
+    expect(manifest.name).toBe('hermes-ui')
     expect(manifest.display).toBe('standalone')
     expect(manifest.start_url).toBe('/#/hermes/chat')
     expect(manifest.icons).toEqual(expect.arrayContaining([