feat(tui): say so in the status bar when the listener took another port

With the login screen's own attempts no longer holding the port, a
session listens somewhere other than the configured port mainly when
another program already holds it. soulseek-rs still falls back to an
ephemeral port there, which is what lets several clients on one machine
share a configured port, and it advertises the port it really bound. A
manual port forward on the router then points at nothing, though, and
the TUI never said so; the CLI already warns.

After login the TUI compares the bound port with the configured one,
using the CLI's rule, and the status bar's title reads "port X in use,
listening on Y" for the rest of the session. A window attached to a
daemon shows nothing: the daemon owns its listener.

Nicotine+ keeps retrying the configured port every five seconds and
Soulseek.NET refuses it; neither falls back. Keeping the fallback and
making it visible is a deliberate difference.

soulseek-rs/src/ui/downloads.rs

@@ -12,6 +12,7 @@ use ratatui::{
     widgets::Paragraph,
 };
 use soulseek_rs::DownloadStatus;
+use std::fmt::Write as _;
 
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 
@@ -54,6 +55,7 @@ pub fn render_download_stats(
     downloads: &[DownloadEntry],
     active_count: usize,
     daemon: Option<&str>,
+    listener_fallback: Option<(u16, u16)>,
 ) {
     let completed = downloads
         .iter()
@@ -79,10 +81,14 @@ pub fn render_download_stats(
 
     let active = active_progress(downloads);
 
-    let title = match daemon {
+    let mut title = match daemon {
         Some(endpoint) => format!("Status · daemon {endpoint}"),
         None => "Status".to_string(),
     };
+    if let Some((configured, bound)) = listener_fallback {
+        let _ =
+            write!(title, " · port {configured} in use, listening on {bound}");
+    }
     let block = pane_block(false).title(plain_title(&title, false));
 
     let inner_area = block.inner(area);