fix(orbit): pending counter ignored merged/declined items

The "X / Y pending" counter in the queue head and the guest-side
gate-check both used `state.queue.filter(non-host).length`, which is the
*history* count — items the host has already approved or declined still
sit in `state.queue` for attribution lookup, so the counter never
decreased. Reported as "3 / 4 pending" with no actual rows in the
approval list.

The merged / declined sets only exist in the host's local store, so the
guest can't filter them out itself. Solution: the host writes an
authoritative `pendingApprovalCount` into the state blob each tick;
guests (and the host's own UI) read it directly, with a fallback to the
old over-counting behaviour for any older client that doesn't write the
field.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/hooks/useOrbitHost.ts

@@ -130,11 +130,24 @@ export function useOrbitHost(): void {
         trackId: t.id,
         addedBy: suggesterByTrack.get(t.id) ?? base.host,
       }));
+      // Authoritative pending count — same predicate the approval list uses
+      // (state.queue minus host-authored, minus merged, minus declined). We
+      // recompute fresh each tick from the *current* store sets so an approve
+      // / decline that happened mid-sweep is reflected on the very next push.
+      const mergedNow = new Set(useOrbitStore.getState().mergedSuggestionKeys);
+      const declinedNow = new Set(useOrbitStore.getState().declinedSuggestionKeys);
+      const pendingApprovalCount = afterShuffle.queue.filter(q =>
+        q.addedBy !== afterShuffle.host
+        && !mergedNow.has(suggestionKey(q))
+        && !declinedNow.has(suggestionKey(q))
+      ).length;
+
       const next: OrbitState = {
         ...afterShuffle,
         ...snapshotPlayerPatch(base.host),
         playQueue,
         playQueueTotal: upcoming.length,
+        pendingApprovalCount,
       };
 
       // 5) Commit locally + push remote.