## Summary
- Rename `date-modified` -> `modified` in all 80 docs and the `docs-check-frontmatter` task
Quartz's `CreatedModifiedDate` plugin recognizes `modified`, `lastmod`, `updated`, and `last-modified` — but not `date-modified`. The wrong field name caused Quartz to ignore frontmatter dates entirely and fall through to filesystem timestamps (UTC inside Dagger), showing Feb 12 on pages built late on Feb 11 PST.
## Test plan
- [x] `mise run docs-check-frontmatter` passes
- [ ] Kick off docs release after merge — verify rendered dates match frontmatter values
Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/158
## Summary
Migrates the docs build pipeline to Dagger (Phase 2 of the Dagger CI adoption plan).
- **Backfill `date-modified` frontmatter** on all 80 docs — Dagger's `--src=.` excludes `.git`, so Quartz can't use git history for page dates. Frontmatter dates work with or without git.
- **New `docs-check-frontmatter` mise task + pre-commit hook** — validates all docs have `title`, `tags`, and `date-modified`
- **New Dagger functions** — `build_changelog` (towncrier in Python container) and `build_docs` (chains changelog → Quartz build in Node container, returns tarball)
- **Simplified CI workflow** — the ~44-line inline Quartz build (clone, npm ci, build, tar, cleanup) is replaced by `dagger call build-docs`. Changelog step remains local on the runner since towncrier needs to modify the host working tree for the git commit.
### Design decisions
- **Towncrier runs twice in CI**: once inside Dagger (for the docs tarball) and once on the runner (for the git commit). This is intentional — Dagger's directory export is additive and can't delete the consumed changelog fragments from the host.
- **Artifact hosting stays on Forgejo Releases** (not migrated to Forgejo Packages as the plan doc originally suggested). That migration can happen independently.
- **`date-modified` frontmatter** preserved even though `build_changelog` installs git — the git there is only for towncrier's `git add` call, not for history. The local iteration story (`dagger call build-docs --src=. --version=dev` with uncommitted changes) depends on frontmatter dates.
### Local iteration
```bash
dagger call build-docs --src=. --version=dev export --path=./docs-dev.tar.gz
tar tf docs-dev.tar.gz | head -20
```
## Deployment and Testing
- [x] `dagger call build-docs --src=. --version=dev` produces valid 1.1MB tarball (149 HTML pages)
- [x] Pre-commit hooks pass (including new `docs-check-frontmatter`)
- [ ] Full `workflow_dispatch` run after merge
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/157
