Enforce unique doc filenames and simple wiki-links (#109)

## Summary
- Rename section index files to match their titles (tutorials.md, reference.md, how-to.md, explanation.md) so all filenames are unique
- Convert all ~47 path-based wiki-links to simple filename format across 15 files
- Update doc-filenames task to no longer skip index.md files
- Update doc-links task to reject path-based links containing '/'

This ensures all wiki-links work correctly in obsidian.nvim by making links resolvable by filename alone.

## Testing
- `mise run doc-filenames` - all unique
- `mise run doc-links` - no broken or path-based links
- `mise run doc-titles` - no duplicates

Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/109

docs/how-to/how-to.md

@@ -0,0 +1,42 @@
+---
+title: how-to
+tags:
+  - how-to
+---
+
+# How-To Guides
+
+Task-oriented instructions for common BlumeOps operations. These guides assume you already understand the basic concepts - see [[tutorials|Tutorials]] if you're learning.
+
+## Deployment
+
+| Guide | Description |
+|-------|-------------|
+| [[deploy-k8s-service]] | Deploy a new service to Kubernetes via ArgoCD |
+| [[add-ansible-role]] | Add a new Ansible role for indri services |
+
+## Configuration
+
+| Guide | Description |
+|-------|-------------|
+| [[update-tailscale-acls]] | Update Tailscale access control policies |
+| [[use-pypi-proxy]] | Configure pip and publish packages to devpi |
+
+## Documentation
+
+| Guide | Description |
+|-------|-------------|
+| [[update-documentation]] | Publish docs via build-blumeops workflow |
+
+## Knowledge Base
+
+| Guide | Description |
+|-------|-------------|
+| [[review-documentation]] | Periodically review and maintain documentation |
+
+## Operations
+
+| Guide | Description |
+|-------|-------------|
+| [[restart-indri]] | Safely shut down and restart indri |
+| [[troubleshooting]] | Diagnose and fix common issues |