feat: memory scope segmentation — wire context scope into perceive gate

Adds *scope-resolver* hook in core-loop-perceive that the context-manager
skill sets at load time. The perceive gate now passes the active scope
to ingest-ast, tagging all ingested objects with the current context scope.

Implementation:
- core-loop-perceive: *scope-resolver* defvar (default nil → :memex),
  two ingest-ast calls now pass (if *scope-resolver* (funcall it) :memex)
- core-defpackage: export *scope-resolver* and context-query
- system-context-manager: auto-init sets *scope-resolver* to #'current-scope

This completes the Memory Scope Segmentation feature: all three scopes
(:memex, :session, :project) are supported, scope-aware retrieval
(context-query :scope / context-scoped-query) was already implemented,
and ingested objects now correctly carry the active scope.

lisp/core-loop-perceive.lisp

@@ -2,6 +2,9 @@
 
 (defvar *loop-interrupt* nil)
 
+(defvar *scope-resolver* nil
+  "If set, function returning current scope keyword. Used by perceive gate.")
+
 (defvar *loop-async-sensors* '(:chat-message :delegation :user-command)
   "Sensors that are processed in dedicated threads.")
 
@@ -79,13 +82,13 @@ FN receives (signal) and returns T if consumed, nil to continue."
                (let ((ast (getf payload :ast)))
                  (when ast
                    (snapshot-memory)
-                   (ingest-ast ast))))
+                   (ingest-ast ast :scope (if *scope-resolver* (funcall *scope-resolver*) :memex)))))
               (:point-update
                (let ((element (getf payload :element)))
                  (when element
                    (snapshot-memory)
                    (setf *loop-focus-id* (getf element :id))
-                   (ingest-ast element))))
+                   (ingest-ast element :scope (if *scope-resolver* (funcall *scope-resolver*) :memex)))))
               (:interrupt
                (setf *loop-interrupt* t))
               ;; HITL: re-injected approved action from dispatcher-approvals-process