Update protocol to not use custom framing

```
message Request {
message CfgSolict { ... }
one of req {
CfgSolict cfgSolict = 1;
}
}

message Reply {
message Cfg { ... }
message Nack { ... }
one of reply {
Cfg cfg = 1;
Nack nack = 2;
}
}
```

The issue provides only a proposed Request and Reply message shape and does not name files, tests, or entry points. Start by locating the protocol implementation and its framing-related tests, then determine the scope of replacing custom framing with the shown message structure. Done means the protocol no longer depends on custom framing and the existing protocol tests pass.

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