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]>

messaging-pubsub/hyper-p2p-subscription-lease/index.js

@@ -165,6 +165,14 @@ class HyperP2PSubscriptionLease extends EventEmitter {
     return this.snapshot().leases
   }
 
+  listKeys () {
+    return this.listChannels()
+  }
+
+  keyCount () {
+    return this.size()
+  }
+
   acquireBatch (channels) {
     if (!Array.isArray(channels)) throw new Error('channels array required')
     return channels.map((ch) => this.acquire(ch))