swarm.js: drop the queue-summary banner rather than ship it on an interim jobq fetch

mara, on the already-approved PR: "dont replace one legacy thing with
another. then we will have to either wait with this pr or split it
into what can and cannot be done now."

Splitting: the transients-only per-agent badge fix is real, correct,
and fixes a live regression (the old DagView fields it read no longer
exist) — nothing about it depends on job-queue data at all, so it
ships as-is. The queue-summary banner is the part that doesn't belong
in this shape: it was reading GET /api/jobq/graph directly and
deriving counts client-side as an interim stand-in for the dedicated
rollup endpoint mara separately asked for — exactly the kind of
stopgap-on-a-stopgap her comment is calling out, since the endpoint
that should serve it doesn't exist on main yet.

Removes jobqNodesState, refreshJobqGraph(), the rebuild_queue_changed
SSE subscription, and the banner's render block from swarm.js/tabs.js
entirely — swarm.js now reads no job-queue state of any kind, fully
satisfying "swarm.js should not need to pull in the jobq to do its
job." The banner comes back once the rollup endpoint
(hyperhive#2985's follow-up) exists, reading that directly instead of
the full graph. Until then the per-agent transient pills still show
what's actually running on each card; only the hive-wide "N running /
M queued" summary line is temporarily gone.

CSS classes for the banner (.queue-summary/.queue-summary-link) kept
in dashboard.css rather than deleted-then-restored — commented as
currently unused, expected to come back unchanged.

docs/web-ui/dashboard.md updated to match (Container-row pending-
badge section, the removed Build-queue-summary-banner section, and
the BU1LDS-page note that used to describe SW4RM's now-removed
parallel fetch).

frontend/packages/dashboard/src/dashboard.css

@@ -458,7 +458,11 @@ hive-agent-menu {
 
 /* Build-queue summary banner on the SW4RM tab: one compact line
    when the rebuild queue has active work, with a link to the full queue on
-   the C0R3 page. Amber to match the in-progress / "rebuilding" card tint. */
+   the C0R3 page. Amber to match the in-progress / "rebuilding" card tint.
+   Currently unused — swarm.js dropped the banner pending a dedicated
+   rollup endpoint (see swarm.js's transients-section comment) — kept
+   here rather than deleted-then-restored, since the markup/classes are
+   expected to come back unchanged once that endpoint exists. */
 .queue-summary {
   display: flex;
   align-items: center;