dashboard + agent UI: surface hive_name + swarm_name in chrome (#701)

Damocles's backend (c41bf1b) landed HYPERHIVE_HIVE_NAME / _SWARM_NAME
env vars and identity.rs accessors. This commit wires them into the two
web surfaces:

hive-c0re/dashboard.rs:
  StateSnapshot gains `hive_name` + `swarm_name` (Option<String>),
  populated from the env vars the c0re NixOS module injects.

hive-ag3nt/web_ui.rs:
  Per-agent StateSnapshot gains the same two fields, populated from
  crate::identity::hive_name() / swarm_name().

Dashboard frontend (index.html + tabs.js):
  A `<p class="banner-thin" id="hive-identity">` sits above the tab
  strip in the chrome. refreshState() populates it with "swarm / hive"
  (or just "hive") when the fields are non-null, and updates
  document.title to "<swarm>/<hive> // h1ve-c0re". No change to
  chrome when both fields are null (backward compat).

Per-agent frontend (index.html + app.js + agent.css):
  A hidden `.agent-hive-label` span under the title row shows the
  swarm/hive label once setHeader() receives non-null names.
  document.title is updated to "<label> // <hive_name>" when hive_name
  is set, enabling browser-tab disambiguation when multiple hives are
  open in parallel. Styled as a small uppercase purple-dim sub-label.

frontend/packages/agent/src/agent.css

@@ -931,3 +931,19 @@ pre.diff {
   font-style: italic;
   padding: 1em 0;
 }
+
+/* Hive identity row — shows "swarm / hive" label beneath the title.
+   Hidden until JS populates from /api/state (hive_name + swarm_name).
+   Mirrors the `.banner-thin` style in dashboard.css but kept tight
+   (no letter-spacing, smaller text) so it reads as a sub-label. */
+.agent-hive-row {
+  /* Omit the default row gap when the row is hidden to avoid a
+     blank gap between the title row and the state row. */
+  gap: 0;
+}
+.agent-hive-label {
+  font-size: 0.72em;
+  letter-spacing: 0.1em;
+  color: var(--purple-dim);
+  text-transform: uppercase;
+}

frontend/packages/agent/src/app.js

@@ -138,7 +138,7 @@ window.marked = marked;
   })();
 
   // ─── state rendering ────────────────────────────────────────────────────
-  function setHeader(label, qualifiedLabel, dashboardPort) {
+  function setHeader(label, qualifiedLabel, dashboardPort, hiveName, swarmName) {
     const title = $('title');
     // Title is just the glowing identity glyph — DASHB04RD, R3BU1LD,
     // NEW SESSION live in the overflow `⋯` menu. Glow + uppercase
@@ -147,15 +147,26 @@ window.marked = marked;
     // the second row's `qualified` chip + the browser tab title so
     // the cinematic header reads cleanly at a glance.
     title.textContent = `◆ ${label} ◆`;
-    // Document title carries the qualified name so the browser's tab
-    // bar disambiguates between same-named agents on different hives
-    // in a federated swarm. Falls back to `${label} // hyperhive` when
-    // the qualified form is just the short label (single-hive deploys).
+    // Document title: prefer the human display names when available
+    // (e.g. "iris // pr1ma") so browser tabs read naturally. Fall back
+    // to the qualified domain label (e.g. "iris@pr1ma.darkest.space")
+    // for multi-hive disambiguation when display names are unset, then
+    // to plain label for single-hive deploys.
+    const hiveLabel = hiveName || null;
     const tab = qualifiedLabel && qualifiedLabel !== label ? qualifiedLabel : label;
-    document.title = `${tab} // hyperhive`;
+    document.title = hiveLabel ? `${label} // ${hiveLabel}` : `${tab} // hyperhive`;
     const dashUrl = `${location.protocol}//${location.hostname}:${dashboardPort}/`;
     dashboardBase = dashUrl;
     populateOverflowMenu(label, dashUrl);
+    // Swarm label in the chrome: show "swarm/hive" when both set, just
+    // "hive" when only hive is known. Targets the `.agent-hive-label`
+    // element in the header row if present.
+    const hiveEl = document.querySelector('.agent-hive-label');
+    if (hiveEl && (hiveName || swarmName)) {
+      hiveEl.textContent = swarmName && hiveName
+        ? `${swarmName} / ${hiveName}` : (hiveName || swarmName);
+      hiveEl.hidden = false;
+    }
   }
 
   // Overflow popover: dashboard back-link + rebuild + new-session +
@@ -1044,7 +1055,7 @@ window.marked = marked;
       const resp = await fetch('api/state');
       if (!resp.ok) throw new Error('http ' + resp.status);
       const s = await resp.json();
-      if (!headerSet) { setHeader(s.label, s.qualified_label, s.dashboard_port); headerSet = true; }
+      if (!headerSet) { setHeader(s.label, s.qualified_label, s.dashboard_port, s.hive_name, s.swarm_name); headerSet = true; }
       currentLabel = s.label;
       // Render server-supplied navigation links — see
       // docs/web-ui.md::Per-agent page (meta-nav) for the NavLink

frontend/packages/agent/src/index.html

@@ -25,6 +25,12 @@
         <nav class="meta agent-nav" id="meta-links"></nav>
       </div>
 
+      <!-- Hive identity line: "swarm / hive" label. Hidden until JS
+           populates it from /api/state (hive_name + swarm_name). -->
+      <div class="agent-header-row agent-hive-row">
+        <span class="agent-hive-label" hidden></span>
+      </div>
+
       <div id="state-row" class="agent-state-row agent-header-row">
         <span id="alive-badge" class="status-badge status-loading" title="harness reachability">…</span>
         <span id="state-badge" class="state-badge state-loading">… booting</span>