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/replication/core-services.md

@@ -10,7 +10,7 @@ tags:
 
 > **Audiences:** Replicator
 >
-> **Prerequisites:** [[tutorials/replication/tailscale-setup | Tailscale Setup]]
+> **Prerequisites:** [[tailscale-setup|Tailscale Setup]]
 
 This tutorial walks through setting up the foundational services that your GitOps infrastructure depends on: a git forge and optionally a container registry.
 
@@ -29,7 +29,7 @@ Forgejo runs directly on your server (not in Kubernetes) because Kubernetes depe
 
 ### Using Ansible (BlumeOps Approach)
 
-BlumeOps manages Forgejo via an Ansible role. See [[reference/ansible/roles | Ansible Roles]].
+BlumeOps manages Forgejo via an Ansible role. See [[roles|Ansible Roles]].
 
 ### Manual Installation
 
@@ -101,7 +101,7 @@ For getting started, you can skip this and use public registries.
 
 ## Next Steps
 
-- [[tutorials/replication/kubernetes-bootstrap | Bootstrap Kubernetes]] - Now that you have a git repo, set up your cluster
+- [[kubernetes-bootstrap|Bootstrap Kubernetes]] - Now that you have a git repo, set up your cluster
 - Configure Forgejo webhooks for ArgoCD (after ArgoCD is running)
 
 ## BlumeOps Specifics