fix(hypatia): farm token key → secret-name (scanner FP on 'secret = …')

git-private-farm.a2ml records only the secret's NAME, but the literal
'secret = "…"' shape trips Hypatia's generic-secret detector (error-level,
fails the gate — seen on nextgen-typing#34 / oblibeny#59). Renamed the key;
no value was ever present.

https://claude.ai/code/session_01GJatEm2TVFSTBEkKXmserJ

Author: claude

.machine_readable/bot_directives/git-private-farm.a2ml

@@ -13,7 +13,7 @@ enabled = true
 target = "hyperpolymath/.git-private-farm"
 event-type = "propagate"
 # Secret NAME only — the value lives in GitHub repo secrets, never here.
-secret = "FARM_DISPATCH_TOKEN"
+secret-name = "FARM_DISPATCH_TOKEN"
 # The dispatch step is gated on token presence (job-level env + step-level
 # `if`), so forks / environments without the secret skip cleanly instead of
 # failing with an empty token.