Preserve bounds in reserved tool schemas (#40719)

## Why

Reserved tool parameter constraints must survive schema parsing so the model receives the declared limits.

## What changed

- Preserve `minimum` and `maximum` as exact JSON numbers.
- Preserve `maxLength` and infer a string schema when it is the only type hint.

## Testing

- Cover bounded integer, number, and string schemas through both parsing paths.
- Verify history and notes tools retain their constraints in app-server model requests.

GitOrigin-RevId: 4cc89722b5b226d595b57232ec3b8e825863faf3

codex-rs/app-server/tests/suite/v2/history_notes_extension.rs

@@ -170,6 +170,31 @@ async fn app_server_uses_configured_notes_backend_for_context_window_hints(
                 "app-server should expose {namespace}.{tool_name} to the model"
             );
         }
+        // Reserved tools must retain their parameter constraints in the model request.
+        for (namespace, tool_name, property, expected) in [
+            (
+                "history",
+                "list_items",
+                "limit",
+                json!({"type": "integer", "minimum": 1, "maximum": 20}),
+            ),
+            (
+                "notes",
+                "search_contents",
+                "query",
+                json!({"type": "string", "maxLength": 1000}),
+            ),
+        ] {
+            let tool = request
+                .tool_by_name(namespace, tool_name)
+                .expect("history/notes tool should be exposed");
+            let mut schema = tool["parameters"]["properties"][property].clone();
+            schema
+                .as_object_mut()
+                .expect("parameter schema")
+                .remove("description");
+            assert_eq!(schema, expected, "{namespace}.{tool_name}.{property}");
+        }
     }
     assert!(request.tool_by_name("notes", "thread_hint").is_none());