Add listKeys() and keyCount() helpers across modules (ninth pass).

Standardize key enumeration after size() on map- and registry-style modules, aliasing existing list* methods or primary store keys so callers can inspect occupancy without parsing snapshots.

Co-authored-by: Cursor <[email protected]>

network-stack/hyper-p2p-overlay-topology/index.js

@@ -108,6 +108,14 @@ class HyperP2POverlayTopology extends EventEmitter {
     return this.snapshot().degree
   }
 
+  listKeys () {
+    return this.neighborIds()
+  }
+
+  keyCount () {
+    return this.size()
+  }
+
   getStats () {
     return { ...this._stats, degree: this._neighbors.size, protocol: PROTOCOL }
   }