sec-shell-exec

# Task

Implement **`solution.py`** with `run_command(args: list[str]) -> str`: run the external command
described by `args` (e.g. `["ls", "-l"]`) and return its stdout as a string.

To solve this problem, we need to implement a function that runs an external command specified by a list of strings and returns the standard output (stdout) of that command as a string. The function should handle both successful commands and those that produce errors, but it should only return the stdout content.

### Approach
The approach to solve this problem involves using Python's `subprocess` module, which allows us to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. Here are the key steps:

1. **Import the Subprocess Module**: We use the `subprocess` module to interact with the system shell and execute commands.
2. **Run the Command**: Use `subprocess.run()` to execute the command specified by the input list. This function allows us to capture the output streams (stdout and stderr) and run the command in a non-blocking manner.
3. **Capture Output**: By setting `stdout=subprocess.PIPE` and `stderr=subprocess.PIPE`, we ensure that both the standard output and standard error are captured. However, since the problem specifically requires only the stdout, we focus on capturing that.
4. **Text Mode**: Setting `text=True` ensures that the output is returned as a string rather than bytes, making it easier to handle and return as required.
5. **Return Stdout**: Extract the stdout from the result of the subprocess.run() call and return it as a string.

### Solution Code

```python
import subprocess

def run_command(args: list[str]) -> str:
    result = subprocess.run(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
    return result.stdout
```

### Explanation
- **subprocess.run()**: This function is used to run the command. It takes the command as a list of strings, where the first string is the command and the subsequent strings are arguments.
- **stdout and stderr Parameters**: By setting `stdout=subprocess.PIPE` and `stderr=subprocess.PIPE`, we capture both the standard output and standard error streams. However, since the problem requires only stdout, we focus on returning `result.stdout`.
- **text=True**: This parameter ensures that the output is returned as a string rather than bytes, which simplifies handling the output.
- **Return Value**: The function returns the captured stdout as a string. If the command does not produce any stdout, an empty string is returned.

This approach efficiently captures and returns the stdout of the executed command, handling both successful executions and those that produce errors without affecting the output.