Avoid JSON-schema canonicalization (preserve field order)

Motivation:
- App-server JSON schema output is already stable; sorting object keys is unnecessary.
- Alphabetical key canonicalization is potentially harmful because it obscures intentional ordering (e.g. struct field order) and makes diffs noisier.

What changed:
- Remove JSON key-sorting from schema emission.
- Regenerate vendored JSON schema fixtures.

Refs: openai/codex#8956 (fixture sync test pattern)

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

@@ -0,0 +1,84 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "ToolRequestUserInputOption": {
+      "description": "EXPERIMENTAL. Defines a single selectable option for request_user_input.",
+      "properties": {
+        "description": {
+          "type": "string"
+        },
+        "label": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "description",
+        "label"
+      ],
+      "type": "object"
+    },
+    "ToolRequestUserInputQuestion": {
+      "description": "EXPERIMENTAL. Represents one request_user_input question and its required options.",
+      "properties": {
+        "header": {
+          "type": "string"
+        },
+        "id": {
+          "type": "string"
+        },
+        "isOther": {
+          "default": false,
+          "type": "boolean"
+        },
+        "isSecret": {
+          "default": false,
+          "type": "boolean"
+        },
+        "options": {
+          "items": {
+            "$ref": "#/definitions/ToolRequestUserInputOption"
+          },
+          "type": [
+            "array",
+            "null"
+          ]
+        },
+        "question": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "header",
+        "id",
+        "question"
+      ],
+      "type": "object"
+    }
+  },
+  "description": "EXPERIMENTAL. Params sent with a request_user_input event.",
+  "properties": {
+    "itemId": {
+      "type": "string"
+    },
+    "questions": {
+      "items": {
+        "$ref": "#/definitions/ToolRequestUserInputQuestion"
+      },
+      "type": "array"
+    },
+    "threadId": {
+      "type": "string"
+    },
+    "turnId": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "itemId",
+    "questions",
+    "threadId",
+    "turnId"
+  ],
+  "title": "ToolRequestUserInputParams",
+  "type": "object"
+}