swarm-ui: rename OverviewPage/'overview' to HivesPage/'hives'

Closes #3460.

Renamed for accuracy — the page/nav item is the hive roster, not a
general dashboard overview. Nav label, page title, component name,
and file all renamed together so the internal name doesn't drift from
what's displayed (a component still called OverviewPage under a
'hives' nav label would be exactly the kind of stale prior-art that
makes the next contributor search harder, not less).

frontend/packages/swarm-ui/src/pages/CreateAgentPage.tsx

@@ -36,7 +36,7 @@ import { SelectField, type SelectOption } from '../ui/select-field/SelectField.j
 import { Button } from '../ui/button/Button.js';
 import './CreateAgentPage.css';
 
-// Mirrors swarm-controller's `HiveEntry` — same shape `OverviewPage`
+// Mirrors swarm-controller's `HiveEntry` — same shape `HivesPage`
 // consumes off `/api/hives/status`, but this page hits the plain
 // `/api/hives` roster (no status/freshness needed, just "what hives
 // exist to spawn into").

frontend/packages/swarm-ui/src/pages/HivesPage.tsx

@@ -1,4 +1,4 @@
-// <OverviewPage> — the hive-roster overview, `/`'s content. Fetches
+// <HivesPage> — the hive roster, `/`'s content. Fetches
 // swarm-controller's `GET /api/hives/status`, the swarm-wide status
 // aggregate: one row per roster hive, freshness derived at read time
 // from the status bucket. Supersedes the earlier `GET /api/hives` +
@@ -60,7 +60,7 @@ const COLUMNS: TableColumn<HiveStatus>[] = [
   },
 ];
 
-export function OverviewPage() {
+export function HivesPage() {
   const [hives, setHives] = useState<HiveStatus[] | null>(null);
   const [error, setError] = useState<ProblemDetails | null>(null);
 
@@ -76,7 +76,7 @@ export function OverviewPage() {
   }, []);
 
   return (
-    <Panel title="overview">
+    <Panel title="hives">
       {error ? <ApiErrorPanel context="failed to load the hive roster" problem={error} /> : null}
       {!error && hives === null ? <p>loading…</p> : null}
       {hives ? <Table columns={COLUMNS} rows={hives} rowKey={(h) => h.name} /> : null}