test(good-fences): show which mower the neighbor gets

The chat and load arrows drew `things: { mower }` whether I lent the
raw mower or the governed one. Name objects by the reply arrow that
introduced them, so the diagram reads `things: { mower: governed }`
and lending the raw mower would fail the trace comparison.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

good-fences/docs/lend-the-mower.md

@@ -38,10 +38,10 @@ sequenceDiagram
   MF-->>F: mower
   F-->>P: govern(mower, 2)
   P-->>F: governed
-  F-->>N: chat({ role, content, things: { mower }, about: { mower } })
-  N-->>L: complete([{ role, content, about: { mower } }])
+  F-->>N: chat({ role, content, things: { mower: governed }, about: { mower: { ts } } })
+  N-->>L: complete([{ role, content, about: { mower: { ts } } }])
   L-->>N: code
-  N-->>TL: load(code, { mower })
+  N-->>TL: load(code, { mower: governed })
   TL-->>N: tenant
   N-->>T: run()
   T-->>G: start()