`miden client exec` cannot take a compiled transaction script package

Reporting here per bitwalker's suggestion in 0xMiden/compiler#1349.

`exec` only accepts MASM source. `--script-path` is read and handed to `CodeBuilder::compile_tx_script`, so passing the `.masp` that `cargo miden build` produces fails with `stream did not contain valid UTF-8` rather than anything about packages. There is no flag for a compiled script on 0.15.0, and `ExecCmd` on `main` still carries a single `script_path`.

The conversion is available in the protocol crate, and I verified it on a package built from a Rust `#[tx_script]`:

```rust
let package = Package::read_from_bytes(&fs::read(path)?)?;
let entrypoint: QualifiedProcedureName =
r#"::"miden:base/transaction-script@1.0.0"::run"#.parse()?;
let tx_script = TransactionScript::from_package(&package.make_executable(&entrypoint)?)?;
```

`TransactionScript::from_package` alone is not enough today, since it turns down a package whose kind is `transaction-script`; `make_executable` is what gets it accepted. That half is 0xMiden/protocol#3769.

So `exec` could dispatch on the file it is given: a `.masp` through the path above, anything else through `compile_tx_script` as now. I am happy to put up a PR, but I would rather not guess between overloading `--script-path` and adding a separate `--package` flag, so say which you would prefer.

I checked the conversion only, not execution of the resulting script against an account.

Look at the `exec` command in the CLI code, likely in `src/cli/commands/exec.rs`. The `ExecCmd` struct currently has a `script_path`. You need to add logic to detect a `.masp` file extension and use `Package::read_from_bytes` and `TransactionScript::from_package` via `make_executable`. Check how `CodeBuilder::compile_tx_script` is called to understand the current flow. Test by building a transaction script package with `cargo miden build` and running `miden client exec` with the resulting `.masp` file.

Scritto dal modello di indicizzazione a partire dal testo della issue.