hermes: add web dashboard service (basic-auth, LAN port 9119)

Add a hermes-dashboard compose service that runs 'hermes dashboard' on
0.0.0.0:9119 with HTTP basic auth. The username + scrypt password hash
live in the git-ignored /home/dank/hermes-data config (plaintext never
stored). A separate container from the Signal gateway, since the gateway
entrypoint does not start the dashboard. Both share the data volume and
are boot-persistent. Docs page + index link added (docs-first contract).

docs/index.md

@@ -38,6 +38,7 @@ This repository tracks the container stacks for both hosts. Git is the single so
 - [[ComfyUI]] — node-based AI image generation (CPU)
 - [[OpenWebUI]] — chat UI for local LLMs
 - [[Hermes]] — the Nous Research agent
+- [[Hermes-Dashboard]] — the Hermes web management UI (config, keys, sessions)
 - [[Gitea]] — Git hosting (migrated)
 - [[Postgres]] — Gitea database backend