feat(memory): add memory extension with core functionality and tests

- Implemented MemoryStore class for managing concepts with YAML frontmatter.
- Added methods for creating, reading, updating, and deleting concepts.
- Introduced locking mechanism for concurrent access.
- Developed search and hinting capabilities for concept retrieval.
- Created tests for access control and store functionality.
- Added long-term memory skill documentation and operational guidelines.
- Included package.json and package-lock.json for dependency management.

extensions/memory/access.mjs

@@ -0,0 +1,50 @@
+export class MemoryTurnAccess {
+  constructor() {
+    this.reset();
+  }
+
+  reset() {
+    this.searched = false;
+    this.searchResultIds = new Set();
+    this.readIds = new Set();
+  }
+
+  recordSearch(ids) {
+    this.searched = true;
+    for (const id of ids) this.searchResultIds.add(id);
+  }
+
+  requireSearchedId(id) {
+    if (!this.searched) {
+      throw new Error("Memory workflow blocked: call memory_search in this user turn before reading or mutating memory.");
+    }
+    if (!this.searchResultIds.has(id)) {
+      throw new Error(`Memory workflow blocked: search for the exact concept '${id}' in this user turn first.`);
+    }
+  }
+
+  recordRead(ids) {
+    for (const id of ids) {
+      this.requireSearchedId(id);
+      this.readIds.add(id);
+    }
+  }
+
+  requireWrite(id, exists) {
+    if (!this.searched) {
+      throw new Error("Memory workflow blocked: call memory_search for duplicates in this user turn before writing.");
+    }
+    if (!exists) return;
+    this.requireSearchedId(id);
+    if (!this.readIds.has(id)) {
+      throw new Error(`Memory workflow blocked: read existing concept '${id}' in this user turn before updating it.`);
+    }
+  }
+
+  requireForget(id) {
+    this.requireSearchedId(id);
+    if (!this.readIds.has(id)) {
+      throw new Error(`Memory workflow blocked: read concept '${id}' in this user turn before forgetting it.`);
+    }
+  }
+}