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/how-to/index.md

@@ -20,6 +20,7 @@ Task-oriented instructions for common BlumeOps operations. These guides assume y
 | Guide | Description |
 |-------|-------------|
 | [[update-tailscale-acls]] | Update Tailscale access control policies |
+| [[use-pypi-proxy]] | Configure pip and publish packages to devpi |
 
 ## Documentation
 

docs/how-to/use-pypi-proxy.md

@@ -0,0 +1,61 @@
+---
+title: use-pypi-proxy
+tags:
+  - how-to
+  - python
+---
+
+# Use the PyPI Proxy
+
+How to configure clients and publish packages to [[devpi]].
+
+## Configure pip
+
+Create `~/.config/pip/pip.conf`:
+
+```ini
+[global]
+index-url = https://pypi.ops.eblu.me/root/pypi/+simple/
+trusted-host = pypi.ops.eblu.me
+```
+
+Track with chezmoi:
+```bash
+chezmoi add ~/.config/pip/pip.conf
+```
+
+## Upload Packages
+
+```bash
+# Build and publish with uv
+cd ~/code/personal/your-package
+uv build
+uv publish --publish-url https://pypi.ops.eblu.me/eblume/dev/
+
+# First time: uv will prompt for credentials
+```
+
+## Create Users/Indices
+
+```bash
+# Login as root
+uvx devpi use https://pypi.ops.eblu.me
+uvx devpi login root
+
+# Create user (prompts for password - store in 1Password)
+uvx devpi user -c USERNAME email=EMAIL
+
+# Create index inheriting from PyPI mirror
+uvx devpi index -c USERNAME/dev bases=root/pypi
+```
+
+## Verify Cache
+
+```bash
+# Check if devpi is caching
+curl -s https://pypi.ops.eblu.me/+api | jq
+```
+
+## Related
+
+- [[devpi]] - Service reference