feat: bring over the formatter from gleam

crates/cli/src/cmd/fmt.rs

@@ -0,0 +1,31 @@
+#[derive(clap::Args)]
+/// Create a new Aiken project
+pub struct Args {
+    /// Files to format
+    #[clap(default_value = ".")]
+    files: Vec<String>,
+
+    /// Read source from STDIN
+    #[clap(long)]
+    stdin: bool,
+
+    /// Check if inputs are formatted without changing them
+    #[clap(long)]
+    check: bool,
+}
+
+pub fn exec(
+    Args {
+        check,
+        stdin,
+        files,
+    }: Args,
+) -> miette::Result<()> {
+    if let Err(err) = aiken_project::format::run(stdin, check, files) {
+        err.report();
+
+        miette::bail!("failed: {} error(s)", err.total());
+    };
+
+    Ok(())
+}