hermes-webui: add Hermex server as loopback compose service on Dankclaw

- compose: hermes-webui runs bootstrap.py --foreground in the agent image,
  shares /home/dank/hermes-data (same uid mapping as the gateway), publishes
  127.0.0.1:8787 only; password from host .env
- planner/remote deployer: hermes-webui is an isolated Dankclaw service
- tests: deployment integrity seam (loopback, auth, volume, healthcheck,
  planner narrowing, deployer dispatch)
- docs: Hermes-WebUI page with the iOS SSH-tunnel access pattern

dankclaw/.env.example

@@ -40,6 +40,11 @@ SIGNAL_ACCOUNT=+15551234567
 # Comma-separated E.164 numbers allowed to message the agent.
 SIGNAL_ALLOWED_USERS=+15551234567
 
+# Hermes web UI (Hermex server) login password. Required: the webui binds to
+# loopback and is reached only through the SSH tunnel, but Hermex still signs
+# in with this password. Set a strong value in the live .env.
+HERMES_WEBUI_PASSWORD=changeme
+
 # Porkbun API (franksdank.cloud + franksdank.casa zones). Caddy uses these
 # for DNS-01 Let's Encrypt wildcard cert issuance. Porkbun API keys are
 # account-wide; rotate them here rather than in the dashboard.