docs: add Vocs documentation site with GitHub Pages deployment

[peetzweg]

Summary

• Set up a Vocs documentation site with individual pages for each layout (month, big, classic, column, oneyear), CLI reference, batch mode guide, and installation instructions
• Added GitHub Actions workflow (deploy-docs.yml) for automatic deployment to GitHub Pages on push to master
• Added CI check that diffs --help output against a committed snapshot to detect docs/CLI drift
• Slimmed down README to link to the full docs site while keeping quick-start and installation sections
• Updated CHANGELOG with docs additions

Setup required after merge

Go to Settings > Pages and set Source to GitHub Actions to enable deployment.

Docs will be available at https://peetzweg.github.io/papr/.

Test plan

• npm run docs:build succeeds, all 11 pages rendered
• All pre-commit checks pass (fmt, clippy, 33 tests)
• After merge: verify GitHub Pages deployment and all page links work
• After merge: enable Pages source as "GitHub Actions" in repo settings

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 29.48%. Comparing base (7887239) to head (1ec9a79).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #58   +/-   ##
=======================================
  Coverage   29.48%   29.48%           
=======================================
  Files          12       12           
  Lines        1550     1550           
=======================================
  Hits          457      457           
  Misses       1093     1093           

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