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/server/src/services/hermes/pets.ts

@@ -133,7 +133,7 @@ async function fetchBytes(urlValue: string, maxBytes: number): Promise<{ buffer:
   const timeout = setTimeout(() => controller.abort(), FETCH_TIMEOUT_MS)
   try {
     const response = await fetch(url, {
-      headers: { 'User-Agent': 'hermes-web-ui-pets' },
+      headers: { 'User-Agent': 'hermes-ui-pets' },
       signal: controller.signal,
     })
     if (!response.ok) throw new Error(`Pet asset request failed: ${response.status}`)