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/chat-view-tab-title.test.ts

@@ -80,7 +80,7 @@ function makeSession(title: string): Session {
 describe('ChatView tab title', () => {
   beforeEach(() => {
     vi.clearAllMocks()
-    document.title = 'Hermes Studio'
+    document.title = 'hermes-ui'
     setActivePinia(createPinia())
 
     const appStore = useAppStore()
@@ -107,7 +107,7 @@ describe('ChatView tab title', () => {
     expect(document.title).toBe('Implementation Notes')
 
     wrapper.unmount()
-    expect(document.title).toBe('Hermes Studio')
+    expect(document.title).toBe('hermes-ui')
   })
 
   it('falls back to the product title when the session title is blank', () => {
@@ -116,7 +116,7 @@ describe('ChatView tab title', () => {
 
     const wrapper = mount(ChatView)
 
-    expect(document.title).toBe('Hermes Studio')
+    expect(document.title).toBe('hermes-ui')
     wrapper.unmount()
   })
 })