chore(orcarouter): repackage to address CI check failures

Adds PRIVACY.md (required for marketplace submission) and requirements.txt
(enables CI's dify_plugin version verification) to the plugin package.

Resolves the 3 CI check failures from PR #2413 review:
- Project structure: missing PRIVACY.md
- PRIVACY.md not found in plugin package
- dify_plugin version not found (CI couldn't pip install without requirements.txt)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: zhenjun.chen