revert(app): cold-start chat seed (it regressed idle-poll budget)

The seedHeadsIfMissing path I added fired N listMessages calls on
first refresh after auth, blowing idle-poll budget (landing went to
11 reqs at 30s). Reverting to the prior behavior:

- Topbar Chat badge shows real unread when localStorage heads are
  populated (i.e. after the user has visited Chat at least once)
- Cold-start (fresh browser / cleared storage) the badge shows 0
  until Chat is opened — same accepted caveat Oracle named on
  sha-c3515707 and PASS'd

Idle-poll budget protected; Wizard 'Manual review' label change
from prior commit stays.

src/App.tsx

@@ -102,28 +102,6 @@ export default function App() {
       }
       return n;
     };
-    // Cold-start: if localStorage heads map is empty/stale (fresh browser,
-    // private window, cleared site data), fetch the last message per thread
-    // ONCE on first mount so the badge isn't lying. Subsequent ticks reuse the
-    // localStorage cache — same idle-poll budget as before.
-    const seedHeadsIfMissing = async (threads: { _key: string }[]) => {
-      try {
-        const existing = JSON.parse(localStorage.getItem(`fm.canvas.chat.heads.${userEmail}`) || "{}");
-        if (Object.keys(existing).length >= threads.length) return;
-      } catch { /* fall through */ }
-      const { chatApi } = await import("./lib/chatApi");
-      const heads: Record<string, { at: string; by: string }> = {};
-      await Promise.all(
-        threads.map(async (t) => {
-          try {
-            const rows = await chatApi.listMessages(t._key);
-            const last = rows[rows.length - 1];
-            if (last) heads[t._key] = { at: last.created_at, by: last.author_email };
-          } catch { /* ignore */ }
-        })
-      );
-      try { localStorage.setItem(`fm.canvas.chat.heads.${userEmail}`, JSON.stringify(heads)); } catch { /* ignore */ }
-    };
     const refresh = async () => {
       try {
         const { chatApi } = await import("./lib/chatApi");
@@ -133,8 +111,6 @@ export default function App() {
           apiMod.workItems().catch(() => []),
         ]);
         if (cancelled) return;
-        await seedHeadsIfMissing(threads);
-        if (cancelled) return;
         setChatUnreadCount(computeUnread(threads.map((t) => t._key)));
         setQueueCount(items.filter((it) => (it as any).tenant_id === tenantId).length);
       } catch { /* ignore */ }