Add a Skill-only Hermes Agent install path

[Sayujaya14]

Fixes #283

Document hermes skills install and ship an optional directory plugin so Hermes can load the existing Node Skill without a Python renderer port.

Problem and value

Hermes Agent can load SKILL.md and run Node, but Archify had no documented install path for it. Cursor, Claude Code, Codex, OpenCode, Raven, and DeepSeek Harness were covered; Hermes users had to guess a symlink into ~/.hermes/skills/.

Scope

• What changed: community Skill-only Hermes path (hermes skills install skills-sh/tt-a1i/archify/archify -y); optional integrations/hermes-agent plugin; README EN/ZH row before DeepSeek Harness; changelog; contract tests; Python cache ignores
• What deliberately did not change: schemas, renderers, viewer runtime, ZIP layout, agent switcher, native Hermes render tools, Python port
• No unrelated changes

Stability impact

• Compatibility and migration risk: none for existing agents; opt-in Hermes docs/plugin only
• Renderer, validator, package, or generated-artifact risk: none
• Failure behavior and rollback path: missing SKILL.md fails closed; uninstall with hermes skills uninstall archify / remove symlink; rollback is delete integrations/hermes-agent and the README row

Tests run

• node --test integrations/hermes-agent/test/plugin-contract.test.mjs — pass
• cd archify && npm ci && npm test — 1000 passed, 27 skipped (no ARCHIFY_CHROME / optional env), 0 failed
• Hermes one-shot: hermes chat -Q -s archify … ran node …/archify.mjs doctor → Archify is ready.
• Optional not run: full diagram authoring in Hermes chat