Deepen indexes-search: APIs, tests, and category docs

Extend all eight index/search packages with practical helpers for app
development and fix semantic-vector getStats() to expose real metrics.

Per-module code:
- bloom-gossip: listKeys(), clear()
- inverted-index: searchAll(and|or), getDocTerms()
- fulltext-lite: search(and|or), suggest(prefix)
- trie-prefix: countPrefix(), autocomplete(limit)
- graph-index: removeEdge(), outDegree(), edgeCount()
- similarity-lsh: nearVector(), bucketCount()
- semantic-vector-index: getStats() delegates to getMetrics() + PROTOCOL export
- spatial-index: listLocalPoints(), pointCount(), protocol in getStats()

Tests added for new APIs across six packages; all indexes-search npm test
suites pass (8/8).

Docs:
- Rewrite indexes-search category README (module table, composition)
- Expand bloom-gossip and semantic-vector architecture notes
- modules/README.md: link indexes-search doc hub

Parent workspace docs/indexes-search/README.md and MODULE_DOC_PASS.md
updated separately (outside this git root).

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

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

@@ -235,8 +235,20 @@ class SpatialIndex extends EventEmitter {
   }
 
 
+  listLocalPoints () {
+    return [...this.localPoints.values()]
+  }
+
+  pointCount () {
+    return this.localPoints.size
+  }
+
   getStats () {
-    return { ...this._stats }
+    return {
+      ...this._stats,
+      points: this.localPoints.size,
+      protocol: SPATIAL_PROTOCOL
+    }
   }
 
   async close () {