Complete Phase 6: documentation cleanup and integration (#97)

## Summary
- Delete `docs/zk/` directory - all useful content migrated to structured docs
- Delete `docs/README.md` - `docs/index.md` is now the documentation root
- Add `devpi` reference card and `use-pypi-proxy` how-to guide
- Add maintenance notes to `indri` reference (sleep prevention, passwordless sudo)
- Add iCloud Photos backup note to `borgmatic` reference
- Rewrite `zk-docs` mise task to prime AI context with key docs instead of legacy cards
- Update `CLAUDE.md` and `README.md` to remove zk references
- Update `exploring-the-docs` with AI context priming section

This completes the Diataxis documentation restructuring. All six phases are now done.

## Deployment and Testing
- [x] Pre-commit hooks pass (including doc-links validator)
- [ ] Build and deploy to docs.ops.eblu.me to verify rendering

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/97

docs/reference/services/borgmatic.md

@@ -25,7 +25,9 @@ Daily backup system using Borg backup, running on indri.
 - `/opt/homebrew/var/forgejo` - Git forge data
 - `~/.config/borgmatic` - Borgmatic config
 - `~/Documents` - Personal documents
-- `~/Pictures` - Photos
+- `~/Pictures` - Photos (see note below)
+
+**iCloud Photos note:** macOS Photos.app defaults to "Optimize Mac Storage" which keeps only thumbnails locally. Borgmatic only backs up what's on disk, so iCloud-only photos are NOT backed up via this method.
 
 **Databases:**
 - `miniflux` on [[postgresql]]

docs/reference/services/devpi.md

@@ -0,0 +1,37 @@
+---
+title: devpi
+tags:
+  - service
+  - python
+---
+
+# devpi (PyPI Proxy)
+
+PyPI caching proxy and private package index.
+
+## Quick Reference
+
+| Property | Value |
+|----------|-------|
+| **URL** | https://pypi.ops.eblu.me |
+| **Namespace** | `devpi` |
+| **ArgoCD App** | `devpi` |
+| **Storage** | 50Gi PVC |
+| **Image** | `registry.ops.eblu.me/blumeops/devpi:latest` |
+
+## Indices
+
+| Index | Purpose |
+|-------|---------|
+| `root/pypi` | PyPI mirror/cache (auto-created) |
+| `eblume/dev` | Private packages (inherits from root/pypi) |
+
+## Credentials
+
+Root password stored in 1Password (blumeops vault), injected via ExternalSecret.
+
+## Related
+
+- [[how-to/use-pypi-proxy]] - Client configuration and package uploads
+- [[argocd]] - Deployment
+- [[1password]] - Secrets management