fix(memory): return relations connected to requested nodes in openNodes/searchNodes

Previously, `openNodes` and `searchNodes` only returned relations where
BOTH endpoints were in the result set (using `&&`). This silently
dropped all relations to/from nodes outside the set — making it
impossible to discover a node's connections without calling `read_graph`
and filtering the entire dataset client-side.

Changed the filter from `&&` to `||` so that any relation with at least
one endpoint in the result set is included. This matches the expected
graph-query semantics: when you open a node, you should see all its
edges, not just edges to other opened nodes.

Fixes #3137

Tests updated and new cases added covering:
- Outgoing relations to nodes not in the open set
- Incoming relations from nodes not in the open set
- Relations connected to a single opened node
- searchNodes returning outgoing relations to unmatched entities

Co-authored-by: Cursor <cursoragent@cursor.com>

src/memory/index.ts

@@ -197,9 +197,10 @@ export class KnowledgeGraphManager {
     // Create a Set of filtered entity names for quick lookup
     const filteredEntityNames = new Set(filteredEntities.map(e => e.name));
   
-    // Filter relations to only include those between filtered entities
+    // Include relations where at least one endpoint matches the search results.
+    // This lets callers discover connections to nodes outside the result set.
     const filteredRelations = graph.relations.filter(r => 
-      filteredEntityNames.has(r.from) && filteredEntityNames.has(r.to)
+      filteredEntityNames.has(r.from) || filteredEntityNames.has(r.to)
     );
   
     const filteredGraph: KnowledgeGraph = {
@@ -219,9 +220,12 @@ export class KnowledgeGraphManager {
     // Create a Set of filtered entity names for quick lookup
     const filteredEntityNames = new Set(filteredEntities.map(e => e.name));
   
-    // Filter relations to only include those between filtered entities
+    // Include relations where at least one endpoint is in the requested set.
+    // Previously this required BOTH endpoints, which meant relations from a
+    // requested node to an unrequested node were silently dropped — making it
+    // impossible to discover a node's connections without reading the full graph.
     const filteredRelations = graph.relations.filter(r => 
-      filteredEntityNames.has(r.from) && filteredEntityNames.has(r.to)
+      filteredEntityNames.has(r.from) || filteredEntityNames.has(r.to)
     );
   
     const filteredGraph: KnowledgeGraph = {