research: pipeline-running signal + spinners so users aren't guessing

The prior flow was ambiguous: after hitting Start research, status
flipped to "processing" and a "Submit for review" button appeared
immediately with no indication that anything was actually running.
Users had to guess whether the pipeline was working or stalled.

Backend surfaces the truth as a signal:
- new topology_runs::active_runs_for_research_topic counts
  queued+running runs whose research_topic_id matches
- TopicDetail includes runs_in_flight: i64 alongside the existing
  status field, so the canvas can distinguish "pipeline still
  working" from "runner stalled".

ResearchCanvas is now honest about state:
- while runs_in_flight > 0, the header status pill grows a cyan
  "N runs in flight" badge with an inline SVG spinner
- the stage-explainer card turns cyan-bordered and shows a
  "pipeline is running" hint, plus copy pointing the user at the
  Agents tier where each teammate's activity streams live
- the "Submit for review (manual)" button is HIDDEN while any run
  is in flight — it's an escape hatch for stalled runs only, not
  the happy-path action. It reappears if runs_in_flight drops to
  zero but the topic is still marked processing, so a stalled
  runner can still be nudged along.
- the canvas polls getTopic every 4s while status is processing/
  publishing or runs_in_flight > 0, so the spinner + outcome swap
  in automatically when the pipeline completes.

ResearchList sidebar:
- each row's status dot becomes a spinner when the topic's status
  is processing or publishing, matching the canvas at a glance
- the list also polls every 6s while ANY topic is active, so
  transitions land in the sidebar without waiting on a parent bump.
  The poll is gated on a derived boolean to avoid effect thrash.

Follow-up: same pattern belongs on LoopsList / LoopsCanvas for
loop iterations in flight — same signal (queued+running runs per
loop) but not wired here.

frontend/src/components/dashboard/ResearchList.tsx

@@ -70,6 +70,29 @@ export function ResearchList({
     };
   }, [refreshKey, localBump]);
 
+  // Light polling while any topic is actively running so the spinner + status
+  // in the sidebar transition automatically without waiting on a parent bump.
+  // Depending only on the boolean prevents the effect from thrashing every
+  // time the polled response substitutes a fresh array.
+  const anyActive = topics.some(
+    (t) => t.status === "processing" || t.status === "publishing",
+  );
+  useEffect(() => {
+    if (!anyActive) return;
+    let alive = true;
+    const tick = async () => {
+      try {
+        const rows = await listTopics();
+        if (alive) setTopics(rows);
+      } catch { /* transient — keep the last snapshot */ }
+    };
+    const handle = setInterval(tick, 6000);
+    return () => {
+      alive = false;
+      clearInterval(handle);
+    };
+  }, [anyActive]);
+
   async function doDelete(id: string) {
     if (busyId) return;
     setBusyId(id);
@@ -228,14 +251,18 @@ export function ResearchList({
                       color: "#8a8a92",
                     }}
                   >
-                    <span
-                      style={{
-                        width: 7,
-                        height: 7,
-                        borderRadius: "50%",
-                        background: dot,
-                      }}
-                    />
+                    {t.status === "processing" || t.status === "publishing" ? (
+                      <MiniSpinner color={dot} />
+                    ) : (
+                      <span
+                        style={{
+                          width: 7,
+                          height: 7,
+                          borderRadius: "50%",
+                          background: dot,
+                        }}
+                      />
+                    )}
                     <span style={{ color: dot }}>{t.status}</span>
                     <span style={{ opacity: 0.5 }}>·</span>
                     <span>{t.outcome_kind.replace("_", " ")}</span>
@@ -344,6 +371,26 @@ export function ResearchList({
   );
 }
 
+function MiniSpinner({ color }: { color: string }) {
+  return (
+    <svg width={10} height={10} viewBox="0 0 20 20" aria-hidden>
+      <g fill="none" stroke={color} strokeWidth="2.6" strokeLinecap="round">
+        <circle cx="10" cy="10" r="7.5" opacity="0.22" />
+        <path d="M17.5 10 A7.5 7.5 0 0 0 10 2.5">
+          <animateTransform
+            attributeName="transform"
+            type="rotate"
+            from="0 10 10"
+            to="360 10 10"
+            dur="0.9s"
+            repeatCount="indefinite"
+          />
+        </path>
+      </g>
+    </svg>
+  );
+}
+
 const dangerBtn: React.CSSProperties = {
   padding: "4px 10px",
   borderRadius: 6,