chore: extract docs deploy into standalone workflow

[0x054]

Summary

• Add .github/workflows/docs.yml — builds Zensical and deploys to GitHub Pages
• Callable via workflow_dispatch (manual) or workflow_call (from Release)
• Release workflow calls docs.yml instead of inlining the job
• Add just docs-deploy → gh workflow run docs.yml --ref main

Usage after merge

just docs-deploy
# or
gh workflow run docs.yml --ref main
gh run watch --workflow docs.yml

Optional ref input defaults to main; override in the Actions UI when dispatching manually.

Test plan

• Merge and run just docs-deploy to publish expenses docs (docs: billable expenses, Log screen, and JSON v2 backup #22)
• Verify Release workflow still calls docs job on next release

Made with Cursor