Add approval:read to informed-decision-sitting-requester (source only)

informed-decision's present_existing intake (INFD-WP-0010, 0e66a33) must GET
an existing approval before presenting it. This grants read only: no consume,
no approve, and the audience, subject, tenant and secret stay the same. The
tests pin the exact scope pair and keep the published JSON equal to the
source row.

The live registry is not changed. docs/sitting-requester-read-scope.md has the
record diff and the founder-run keycape-client.py remove/add/restart steps,
and lists the railiance-platform and informed-decision copies that still pin
create-only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 5502@bnt-lap001
Assistant-Session: 68b3b02f-5d0f-4e71-8421-796f62e50196

docs/sitting-requester-registration.json

@@ -3,7 +3,8 @@
   "displayName": "Informed Decision compact-sitting approval requester",
   "audience": "approval-engine",
   "allowedScopes": [
-    "approval:create"
+    "approval:create",
+    "approval:read"
   ],
   "grantTypes": [
     "client_credentials"