dashboard: serve the dashboard at /, fold kept state in as a tab, add a pages menu

Drop the H0M3 tile hub and the core page. The dashboard is now the index;
kept state is its fifth tab. A pages menu in the chrome links flow, stats,
API docs and the swarm UI. The swarm apex URL comes from
services.hyperhive.swarm.domain via HIVE_SWARM_PUBLIC_URL and the new
swarm_public_url field of the state snapshot.

frontend/packages/dashboard/src/flow.js

@@ -5,7 +5,7 @@
 //
 // Does NOT contain the dashboard's tab renderers, mutation-event
 // dispatchers, or refreshState — that's `./tabs.js`, loaded only by
-// /dashboard.html. The flow page runs purely on the broker stream + an
+// the dashboard. The flow page runs purely on the broker stream + an
 // initial /api/state fetch (compose autocomplete needs the live
 // container list).
 
@@ -24,7 +24,7 @@ import { epochSec } from "./util.js";
 
   // ─── local containers cache (for compose autocomplete) ──────────────────
   // The compose box's @-mention completion suggests known agent names.
-  // /dashboard.html (tabs.js) maintains the canonical `containersState`
+  // the dashboard (tabs.js) maintains the canonical `containersState`
   // from /api/state + SSE; here we keep a small local mirror updated
   // by the same `container_state_changed` / `container_removed` events
   // the dashboard would handle.
@@ -261,7 +261,7 @@ import { epochSec } from "./util.js";
         // Drop every other mutation kind silently — without this
         // they'd fall through to the terminal module's default
         // renderer and clutter the log with JSON dumps. The dashboard
-        // tabs handle these on /dashboard.html via tabs.js.
+        // tabs handle these on the dashboard via tabs.js.
         _default: () => {},
       },
       // Re-sync the local containers cache on every SSE (re)connect.