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/tutorials/tutorials.md

@@ -0,0 +1,48 @@
+---
+title: tutorials
+tags:
+  - tutorials
+---
+
+# Tutorials
+
+Learning-oriented guides for understanding and working with BlumeOps.
+
+## Audience Guide
+
+Each tutorial indicates which audiences it serves:
+
+| Icon | Audience | Description |
+|------|----------|-------------|
+| **Owner** | Erich | Quick recall and operational refreshers |
+| **AI** | Claude/AI agents | Context for AI-assisted operations |
+| **Reader** | External readers | Understanding what BlumeOps is |
+| **Contributor** | Operators/contributors | Helping with BlumeOps development |
+| **Replicator** | Replicators | Building your own similar setup |
+
+## Getting Started
+
+| Tutorial | Audiences | Description |
+|----------|-----------|-------------|
+| [[exploring-the-docs]] | All | How to navigate and use this documentation |
+| [[ai-assistance-guide]] | AI, Owner | Context for effective AI-assisted operations |
+
+## Contributing
+
+| Tutorial | Audiences | Description |
+|----------|-----------|-------------|
+| [[contributing]] | Contributor | Your first contribution to BlumeOps |
+| [[adding-a-service]] | Contributor, Replicator | Deploy a new service via ArgoCD |
+
+## Replication
+
+For those building their own homelab GitOps setup.
+
+| Tutorial | Audiences | Description |
+|----------|-----------|-------------|
+| [[replicating-blumeops]] | Replicator | Overview: building a similar environment |
+| [[tailscale-setup|Tailscale Setup]] | Replicator | Setting up Tailscale networking |
+| [[core-services|Core Services]] | Replicator | Forgejo and container registry |
+| [[kubernetes-bootstrap|Kubernetes Bootstrap]] | Replicator | Bootstrapping a Kubernetes cluster |
+| [[argocd-config|ArgoCD Config]] | Replicator | Configuring GitOps with ArgoCD |
+| [[observability-stack|Observability Stack]] | Replicator | Metrics, logs, and dashboards |