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/skills/markdown-viewer/SKILL.md

@@ -2,7 +2,7 @@
 name: markdown-viewer
 description: "Create rich diagrams, data visualizations, technical architecture views, and editorial content cards directly in Markdown using the Markdown Viewer Agent Skills pack. Use for Mermaid-like diagram requests, PlantUML architecture diagrams, Vega charts, JSON Canvas maps, infographics, UML, cloud/network/security/data/IoT diagrams, and polished Markdown documentation visuals."
 version: 1.0.0
-author: Ekko
+author: hermes-ui
 license: MIT
 platforms: [linux, macos, windows]
 metadata: