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.

crates/cm-db/src/repo/topology_runs.rs

@@ -147,6 +147,26 @@ pub async fn enqueue_run_for_team(
     Ok(())
 }
 
+/// Count `queued` + `running` runs whose `research_topic_id` matches. The
+/// research canvas polls this so it can show a spinner "the pipeline is
+/// running" and suppress the manual "Submit for review" escape hatch
+/// while any run is still in flight.
+pub async fn active_runs_for_research_topic(
+    pool: &PgPool,
+    research_topic_id: Uuid,
+) -> Result<i64, DbError> {
+    let row = sqlx::query!(
+        "SELECT count(*) AS n
+           FROM topology_runs
+          WHERE research_topic_id = $1
+            AND status IN ('queued', 'running')",
+        research_topic_id,
+    )
+    .fetch_one(pool)
+    .await?;
+    Ok(row.n.unwrap_or(0))
+}
+
 /// The research topic this run belongs to, if any. Used by the topology
 /// worker's `freeze_research_outcome` post-hook to snapshot the run's
 /// final synthesis into `research_outcomes`.