feat(agents): pin dispatched judgment agents to opus — Fable = inline reflection only (BDR-076)

Reverses the BDR-066 rejected alternative (opus pins on audit agents):
session default is now Fable, so inherit burned Fable quota on every
dispatched audit/challenge. analyzer, plan-challenger, seo/geo/
validator-analyzer pinned model: opus; onboard's 6 general-purpose
audit dispatches carry model="opus"; tour Phase B repointed.
interviewer + client-handover-writer stay unpinned (inline-load only,
a pin there is inert). settings.json default: claude-fable-5[1m].
Census flipped: model-routing §3 + new §11 (61 pass), loops-light 35,
full make test green.

settings.json

@@ -250,7 +250,7 @@
     "disableBypassPermissionsMode": "disable",
     "additionalDirectories": []
   },
-  "model": "opus[1m]",
+  "model": "claude-fable-5[1m]",
   "hooks": {
     "SessionStart": [
       {