Service-layer plumbing for bounded watch-history loading (slice B part 2).
manager.resolve() now forwards chunkDecryptLimit to fetch() and records the
resulting deferred-chunk count in a per-actor side-channel, so resolve() keeps
returning a bare items array (its sole caller depends on that) while the
"more older chunks available" signal is still retrievable. Exposed via
getWatchHistoryDeferredChunkCount() on the manager and the NostrClient facade.
clear() resets the side-channel.
Still inert by default (no caller passes a finite limit yet); this is the
substrate for activating fast-first-render. Tested: resolve under
chunkDecryptLimit:1 returns only the newest chunk's items and reports
deferredChunkCount=1, reset to 0 after clear().
Co-Authored-By: Claude Opus 4.8 <[email protected]>
