fix: gitea runner workingDir, README updates, monitoring domain

- Fix act-runner workingDir: /data on both init and main containers so
  .runner registration file is found at daemon startup
- Add servers/legion/README.md with full service catalog and deploy docs
- Update root README.md to be an index pointing to key docs
- Fix monitoring.tf comment: grafana.neuralplatform.ai (not nook.family)
- Fix AGENTS.md router model to TP-Link Deco BE5000

README.md

@@ -1,16 +1,20 @@
 # infrastructure
 
-Personal infrastructure-as-code — servers, networking, DNS, and config.
+Personal infrastructure-as-code for Legion (k3s home server) and supporting tooling.
 
-## Structure
+| Doc | What it covers |
+|-----|---------------|
+| [`AGENTS.md`](AGENTS.md) | Full reference: machines, secrets, services, domains, namespaces, common operations |
+| [`servers/legion/README.md`](servers/legion/README.md) | What's running on Legion and how deployment works |
+| [`servers/legion/RUNBOOK.md`](servers/legion/RUNBOOK.md) | Disaster recovery — full restore from scratch |
 
-- `servers/legion/` — Legion k3s cluster (Terraform)
-
-## Usage
+## Quick start
 
 ```bash
 cd servers/legion
-direnv allow   # loads credentials from ~/Secrets/credentials/infrastructure.env
+direnv allow
 terraform plan
 terraform apply
 ```
+
+Push to `servers/` to deploy app changes via Argo CD.