One-shot send:
```bash
cargo run --bin mctx_send -- 239.1.2.3 5000 hello
```
Burst send with count and delay:
```bash
cargo run --bin mctx_send -- 239.1.2.3 5000 hello 100 10
```
Tokio variant:
```bash
cargo run --features tokio --bin mctx_tokio_send -- 239.1.2.3 5000 hello 100 10
```
Argument order:
`<group> <port> <payload> [count] [interval_ms]`