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

servers/legion/apps/gitea-runner.yaml

@@ -18,6 +18,7 @@ spec:
       initContainers:
         - name: register
           image: gitea/act_runner:latest
+          workingDir: /data
           command: ["/bin/sh", "-c"]
           args:
             - |
@@ -36,6 +37,7 @@ spec:
       containers:
         - name: runner
           image: gitea/act_runner:latest
+          workingDir: /data
           command: ["act_runner", "daemon"]
           envFrom:
             - secretRef: