feat: Context Manager skill + org-object→memory-object fix

- system-context-manager (new skill): stack-based project focusing with
  push-context/pop-context, path resolution relative to base path, and
  scope-aware memory queries via context-scoped-query.
- core-memory: add :scope slot to memory-object struct (default :memex).
- core-memory: ingest-ast accepts &key (scope :memex), propagates to children.
- core-context: context-query accepts :scope parameter for filtering.
- DEFECT FIX: renamed org-object-* accessors to memory-object-*
  across core-context, security-dispatcher, tests, and defpackage exports.
  The struct was renamed but accessor references were never updated —
  the code referenced nonexistent functions.

lisp/core-defpackage.lisp

@@ -26,23 +26,24 @@
    #:skill-gateway-link
    #:gateway-manager-main
    #:ingest-ast
-   #:lookup-object
+   #:memory-object-get
    #:list-objects-by-type
    #:org-id-new
    #:*memory-store*
    #:*history-store*
-   #:org-object
-   #:make-org-object
-   #:org-object-id
-   #:org-object-type
-   #:org-object-attributes
-   #:org-object-parent-id
-   #:org-object-children
-   #:org-object-version
-   #:org-object-last-sync
-   #:org-object-vector
-   #:org-object-content
-   #:org-object-hash
+   #:memory-object
+   #:make-memory-object
+   #:memory-object-id
+   #:memory-object-type
+   #:memory-object-attributes
+   #:memory-object-parent-id
+   #:memory-object-children
+   #:memory-object-version
+   #:memory-object-last-sync
+   #:memory-object-vector
+   #:memory-object-content
+   #:memory-object-hash
+   #:memory-object-scope
    #:snapshot-memory
    #:rollback-memory
    #:context-query-store