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/common.js

@@ -1,4 +1,4 @@
-// Shared dashboard helpers used by both dashboard.html (./tabs.js) and
+// Shared dashboard helpers used by both index.html (./tabs.js) and
 // flow.html (./flow.js): pure DOM helpers, the side-panel singleton,
 // and the path-link / file-preview infrastructure for the side panel.
 
@@ -564,7 +564,7 @@ export function appendLinkified(parent, text, refs) {
 
 // ─── server warnings banner ──────────────────────────────────────────
 // A generic top-of-page banner shown on every page (dashboard + the
-// stand-alone FL0W / H0M3 pages). The backend decides what to
+// stand-alone FL0W / ST4TS pages). The backend decides what to
 // warn about — `/api/state.server_warnings` is a list of
 // `{ kind, level, message }` — and this just renders it, coloured by
 // `level` (`warn` amber / `crit` red). Adding a new system warning is a
@@ -575,8 +575,8 @@ export function appendLinkified(parent, text, refs) {
 // banner above the page's chrome (tab bar / page header), so the banner
 // stacks with the chrome instead of being overlaid by it (two separate
 // `top:0` stickies would otherwise collide). Built once by wrapping the
-// page's existing chrome element; pages without a chrome (e.g. the H0M3
-// hub) get a banner-only sticky region at the top of <body>.
+// page's existing chrome element; pages without a chrome (none today)
+// get a banner-only sticky region at the top of <body>.
 function ensureStickyTop() {
   let top = document.querySelector(".sticky-top");
   if (top) return top;