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/build.mjs

@@ -43,7 +43,7 @@ mkdirSync(staticDir(''), { recursive: true });
 // follow-up once asset sizes warrant it). esbuild writes each entry
 // to `static/<name>.js` based on the entryPoint basename.
 await build({
-  entryPoints: [src('tabs.js'), src('flow.js'), src('logs.js')],
+  entryPoints: [src('tabs.js'), src('flow.js'), src('logs.js'), src('home.js')],
   outdir: staticDir(''),
   bundle: true,
   format: 'esm',
@@ -81,7 +81,7 @@ await build({
 // (the standalone Catppuccin palette — kept its own file so a theme
 // swap replaces only it) + common.css (shared typography, badges,
 // buttons, inbox, side panel) plus its own page-specific bundle.
-for (const entry of ['theme.css', 'common.css', 'dashboard.css', 'flow.css', 'logs.css']) {
+for (const entry of ['theme.css', 'common.css', 'dashboard.css', 'flow.css', 'logs.css', 'home.css']) {
   await build({
     entryPoints: [src(entry)],
     outfile: staticDir(entry),
@@ -91,7 +91,7 @@ for (const entry of ['theme.css', 'common.css', 'dashboard.css', 'flow.css', 'lo
   });
 }
 
-for (const html of ['index.html', 'flow.html', 'logs.html']) {
+for (const html of ['index.html', 'flow.html', 'logs.html', 'home.html']) {
   copyFileSync(src(html), dist(html));
 }