feat(frontend): add the H0M3 menu-hub page (#1464 step 1)

First step of the dashboard-tab consolidation (#1464): a static menu
page linking to every top-level surface, so the tab strip can later
shed its `→` page-links and the dashboard can graduate Stats/Settings
to their own pages.

- dashboard/src/home.{html,css,js}: a responsive grid of link tiles
  (D4SHB04RD, FL0W, L0GS, M4TR1X). Pure portal — no tabbar/SSE. Colours
  from the shared theme.css, base typography from common.css. The
  Matrix tile is hidden until home.js confirms `matrix_gui_enabled`
  (same gating as the dashboard's M4TR1X tab); home.js also fills the
  swarm/hive identity line.
- build.mjs: emit home.{html,css,js}.

Served at `/home.html` for now (additive — reachable via the existing
ServeDir, links to surfaces at their current routes). Promoting it to
`/` (and relocating the dashboard to `/dashboard` + wiring `← home`
back-links) is the next step — a route swap that touches hive-c0re's
static router, coordinating with damocles. Deliberately decoupled so
this page ships standalone without conflicting with the in-flight
tabs.js change (#1449/#1451).

Part of #1464.

frontend/packages/dashboard/src/home.js

@@ -0,0 +1,33 @@
+// H0M3 page script (#1464). The page is static markup; this only does
+// two small things off a single `/api/state` read:
+//   1. reveal the Matrix tile when the matrix GUI is enabled (same
+//      gating as the dashboard's M4TR1X tab — no dead link otherwise);
+//   2. fill the swarm/hive identity line when configured.
+// No SSE, no shared deps — a portal doesn't need live updates.
+
+const $ = (id) => document.getElementById(id);
+
+async function init() {
+  let state;
+  try {
+    const resp = await fetch('/api/state');
+    if (!resp.ok) return;
+    state = await resp.json();
+  } catch {
+    return; // best-effort: the tiles still work without it
+  }
+
+  if (state.matrix_gui_enabled) {
+    const tile = $('home-tile-matrix');
+    if (tile) tile.hidden = false;
+  }
+
+  const ident = $('hive-identity');
+  if (ident && (state.swarm_name || state.hive_name)) {
+    const parts = [state.swarm_name, state.hive_name].filter(Boolean);
+    ident.textContent = parts.join(' / ');
+    ident.hidden = false;
+  }
+}
+
+init();