feat: add direct Raven installation

[Yangtze-Seventh]

Summary

• add a repository-owned Raven installer that downloads the committed archify.zip directly
• install Archify into Raven's default ~/.raven/workspace/skills/archify path without relying on a third-party Skill installer
• support custom Raven workspaces and local archive sources
• refuse to overwrite an existing installation and run archify doctor after installation
• document Raven in English and Chinese and add regression coverage

Usage

curl -fsSL https://raw.githubusercontent.com/tt-a1i/archify/main/scripts/install-raven.sh \
  -o install-raven.sh
bash install-raven.sh

Custom workspace:

bash install-raven.sh --workspace /path/to/raven-workspace

Testing

• node --test archify/test/raven-onboarding.test.mjs archify/test/readme-showcase.test.mjs archify/test/cursor-onboarding.test.mjs — 8 tests passed
• bash -n scripts/install-raven.sh
• git diff --check
• isolated HOME end-to-end installation from the committed archify.zip
  • Raven skill list and skill get discovered Archify
  • archify doctor passed
  • Archify generated a working demo HTML
  • repeat installation refused to overwrite the existing Skill

The full suite's golden, schema, validator, and version checks passed. In the managed sandbox, the remaining full-suite failures were unrelated: localhost preview tests cannot bind 127.0.0.1 (EPERM), and existing Landing assertions do not match the current checked-in docs/index.html.