test(vision-manager): extract refresh_running_after_mem_check; assert log distinguishes fix from bug (0.87.18)

Two 0.87.15 ship-blockers:

1. mem_check_and_stop test now ALSO greps for the "deferring to next
   tick" warning — distinguishes fix from bug. Mutation-confirmed.

2. Extract `refresh_running_after_mem_check` (sets global instead of
   echoing so loop-scope flags persist across calls) and drive it
   directly from the harness, closing the structurally-untestable
   post-mem refresh ERR guard.

Adjacent: log-on-flip gating on both ERR warnings; `log` to stderr;
dangling-TempDir in app::tests reclaim test fixed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.87.17",
+  "version": "0.87.18",
   "private": true,
   "type": "module",
   "scripts": {