perf(feed): don't block fresh load on remote admin-list fetch

loadVideos awaited ensureAccessControlReady -> waitForReady -> _performRefresh
-> loadAdminState, which awaits a remote admin-list fetch. On a cold load that
waits for relays to connect (~5s) plus the fetch, stalling the feed ~10s before
any video renders. The cached admin state IS hydrated synchronously at
construction, but with markLoaded:false, so waitForReady blocked on a full
remote refresh even when a usable cache existed ("refresh fixes it").

ensureAccessControlReady now blocks only on a first-ever cold load WITH whitelist
mode (where showing non-whitelisted content before the whitelist arrives would be
wrong). In every other case — admin state hydrated from the localStorage cache,
already loaded, or blacklist-only mode — it kicks the refresh off in the
background (ensureReady) and renders immediately; the reactive
onWhitelist/onBlacklistChange handlers re-filter the grid once fresh lists land.

Adds accessControl.isHydrated() and a branching test
(nostr-service-access-control-ready.test.mjs).

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

js/accessControl.js

@@ -460,6 +460,14 @@ class AccessControl {
     return this.whitelistEnabled;
   }
 
+  // True once we have usable lists to filter with — either a completed refresh
+  // or admin state hydrated synchronously from the localStorage cache at
+  // construction. Callers use this to avoid blocking the feed on a remote
+  // refresh when cached lists already allow accurate canAccess() checks.
+  isHydrated() {
+    return this.hasLoaded === true || this._hydratedFromCache === true;
+  }
+
   isSuperAdmin(npub) {
     const normalized = normalizeNpub(npub);
     return normalized ? normalized === ADMIN_SUPER_NPUB : false;