nip71: defer ingest until feed renders; diagnose display path

Live logs proved ingest works (subscribed to 17 whitelisted authors,
received 61 events, injected 39) — but injecting foreign authors during
cold-start triggers the moderation/WoT stage to hydrate their social graph
(kind 30000), which competes with the initial feed load and stalls it
("Fetching recent videos…" hanging, needs a refresh).

- startWhenFeedReady(): defer the first ingest subscription until the
  native feed's first videos:updated (with a 12s fallback for empty
  feeds), keeping ingest off the cold-start critical path. Wired in
  applicationBootstrap (kept thin so the size cap holds).
- emitRefresh now logs how many ingested videos survive the feed filter
  ("N ingested of M in filtered feed") so we can tell whether foreign
  videos are filtered out vs. injected-but-not-rendered.

Tests: defer-until-feed-ready + fallback-timer; mutation-verified.
1236/1237 unit (known UploadModal flake).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/ui/applicationBootstrap.js

@@ -858,6 +858,12 @@ export default class ApplicationBootstrap {
     // Inbound NIP-71 ingest: pull video events published by other Nostr apps
     // (scoped to whitelisted authors while whitelist mode is on) and surface
     // them in the feed. Gated by FEATURE_NIP71_INGEST. Best-effort.
+    //
+    // Deferred until the native feed has rendered once: injecting foreign
+    // authors triggers the moderation/WoT stage to hydrate their social graph
+    // (kind 30000), which during cold-start competes with the initial feed load
+    // and can stall it. Starting after the first videos:updated keeps ingest off
+    // the critical path; a fallback timer covers the empty-feed case.
     const nip71IngestService = createNip71IngestService({
       nostrClient,
       nostrService: app.nostrService,
@@ -865,11 +871,7 @@ export default class ApplicationBootstrap {
     });
     app.nip71IngestService = nip71IngestService;
     if (nip71IngestService.isAvailable()) {
-      try {
-        nip71IngestService.start();
-      } catch (error) {
-        devLogger.warn("[applicationBootstrap] NIP-71 ingest start failed", error);
-      }
+      nip71IngestService.startWhenFeedReady();
       nostrUnsubscribes.push(() => nip71IngestService.stop());
     }
     nostrUnsubscribes.push(