Fix temporal persistence wiring and restore slurp_full suite

pkg/slurp/storage/errors.go

@@ -0,0 +1,8 @@
+package storage
+
+import "errors"
+
+// ErrNotFound indicates that the requested context does not exist in storage.
+// Tests and higher-level components rely on this sentinel for consistent handling
+// across local, distributed, and encrypted backends.
+var ErrNotFound = errors.New("storage: not found")