fix(docker): loopback dashboard bind + shared netns for hermes-agent auth gate

[rameshio]

What changed

• Bind the Hermes Agent dashboard to 127.0.0.1 instead of 0.0.0.0 in docker-compose.yml.
• Run the hermes-workspace container with network_mode: 'service:hermes-agent' (shared network namespace) so it can still reach the dashboard and gateway over loopback.
• Publish port 3000 on the hermes-agent service, since a container joining another service's network namespace cannot publish its own ports.

Why

nousresearch/hermes-agent:latest (June 2026 hardening, post hermes-0day campaign) refuses to bind the dashboard to any non-loopback host unless an auth provider is registered — there is no longer an unauthenticated public-bind option. This breaks the stock compose setup in two ways:

1. With no auth provider configured, the agent exits at startup (Refusing to bind dashboard to 0.0.0.0) and never becomes healthy, so docker compose up fails on the service_healthy dependency.
2. With a password provider configured, the dashboard root 302s to a login page, so the workspace can never scrape the ephemeral session token (fetchDashboardToken in src/server/gateway-capabilities.ts). Every dashboard-backed API then 401s and the chat UI shows "Authentication required — Hermes Agent rejected the connection token", even when API_SERVER_KEY/HERMES_API_TOKEN match correctly.

A loopback bind keeps the auth gate disengaged (trusted-operator model upstream intends for loopback), and the shared network namespace keeps the dashboard reachable from the workspace while making it less exposed than before — it is no longer on the compose bridge network at all.

Notes for reviewers

• Verified on Windows 11 + Docker Desktop with the prebuilt images: agent becomes healthy, dashboard root returns 200 from the workspace container, capability probe reports missing=[] (sessions, skills, memory, config, jobs all available), and the auth banner is gone.
• Host-published ports are unchanged in spirit: 127.0.0.1:3000 (workspace UI) and 127.0.0.1:8642 (gateway); 9119 remains unpublished.
• The gateway keeps API_SERVER_HOST: 0.0.0.0 + API_SERVER_KEY auth as before; only the dashboard moves to loopback.

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