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]>

indexes-search/hyper-spatial-index/index.js

@@ -297,6 +297,15 @@ class SpatialIndex extends EventEmitter {
     return s.points
   }
 
+  async listKeys () {
+    return [...this.localPoints.keys()]
+  }
+
+  async keyCount () {
+    const s = await this.snapshot()
+    return s.points
+  }
+
   getStats () {
     return {
       ...this._stats,