Preserve display instructions in answer moderation (#60172)

## Why

Recovered answer history needs presentation instructions alongside the moderation flag so clients can apply the intended display behavior.

## What changed

- Add optional `display` metadata with an `action` and optional `blockType`, `cyberTrustedAccess`, and `checkTrustedContacts` fields.
- Carry display metadata through final answers, legacy events, thread history reconstruction, and legacy rollout migration.
- Expose the metadata in the app-server protocol and update generated JSON schemas, TypeScript types, and Python SDK models. Missing display fields remain compatible with existing stored moderation data; the app-server emits absent optional values as `null`.

## Testing

Extend the final-answer moderation test to cover display metadata in answer items and legacy events. Add serialization coverage for missing display data, nullable fields, and preservation of an explicit `false` value.

GitOrigin-RevId: b798a2ecc53c2a94c7659ef3d9663b3143b70a1a

codex-rs/app-server-protocol/schema/json/ServerNotification.json

@@ -177,8 +177,49 @@
       ],
       "type": "object"
     },
+    "AgentMessageDisplay": {
+      "description": "A presentation instruction for Chat to apply to this answer when recovering history.",
+      "properties": {
+        "action": {
+          "description": "Unknown actions must be left for the producing client to handle.",
+          "type": "string"
+        },
+        "blockType": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "checkTrustedContacts": {
+          "type": [
+            "boolean",
+            "null"
+          ]
+        },
+        "cyberTrustedAccess": {
+          "type": [
+            "boolean",
+            "null"
+          ]
+        }
+      },
+      "required": [
+        "action"
+      ],
+      "type": "object"
+    },
     "AgentMessageModeration": {
       "properties": {
+        "display": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/AgentMessageDisplay"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
         "moderated": {
           "type": "boolean"
         }