feat(core) RequestRule (#9489)

## Summary
Instead of trying to derive the prefix_rule for a command mechanically,
let's let the model decide for us.

## Testing
- [x] tested locally

codex-rs/core/config.schema.json

@@ -189,6 +189,9 @@
             "remote_models": {
               "type": "boolean"
             },
+            "request_rule": {
+              "type": "boolean"
+            },
             "responses_websockets": {
               "type": "boolean"
             },
@@ -1184,6 +1187,9 @@
         "remote_models": {
           "type": "boolean"
         },
+        "request_rule": {
+          "type": "boolean"
+        },
         "responses_websockets": {
           "type": "boolean"
         },