Refactor user_output.rs into folder module structure

src/presentation/user_output/channel.rs

@@ -0,0 +1,27 @@
+//! Output channel routing for user-facing messages
+//!
+//! This module defines the channel enum that determines whether messages
+//! should be written to stdout or stderr.
+
+/// Output channel for routing messages
+///
+/// Determines whether a message should be written to stdout or stderr.
+/// Following Unix conventions:
+/// - **stdout**: Final results and structured data for piping/redirection
+/// - **stderr**: Progress updates, status messages, operational info, errors
+///
+/// # Examples
+///
+/// ```rust
+/// use torrust_tracker_deployer_lib::presentation::user_output::Channel;
+///
+/// let channel = Channel::Stdout;
+/// assert_eq!(channel, Channel::Stdout);
+/// ```
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Channel {
+    /// Standard output stream for final results and data
+    Stdout,
+    /// Standard error stream for progress and operational messages
+    Stderr,
+}