dashboard: show GATEWAY_HEALTH_URL instead of PID for remote gateways

When the dashboard connects to a remote gateway via GATEWAY_HEALTH_URL,
display the URL instead of the remote PID (which is meaningless locally).
Falls back to PID display for local gateways as before.

- Backend: expose gateway_health_url in /api/status response
- Frontend: prefer gateway_health_url over PID in gatewayValue()
- Add truncate + title tooltip for long URLs that overflow the card
- Add min-w-0/overflow-hidden on status cards for proper truncation
- Tests: verify gateway_health_url in remote and no-URL scenarios

tests/hermes_cli/test_web_server.py

@@ -1122,6 +1122,7 @@ class TestStatusRemoteGateway:
         assert data["gateway_running"] is True
         assert data["gateway_pid"] == 999
         assert data["gateway_state"] == "running"
+        assert data["gateway_health_url"] == "http://gw:8642"
 
     def test_status_remote_probe_not_attempted_when_local_pid_found(self, monkeypatch):
         """When local PID check succeeds, the remote probe is never called."""
@@ -1158,6 +1159,7 @@ class TestStatusRemoteGateway:
         assert resp.status_code == 200
         data = resp.json()
         assert data["gateway_running"] is False
+        assert data["gateway_health_url"] is None
 
     def test_status_remote_running_null_pid(self, monkeypatch):
         """Remote gateway running but PID not in response — pid should be None."""