feat(tui): give the panes the colour the demo promised

The cursor row set a foreground, and ratatui only skips a cell's colour
when that field is None — so selecting a row repainted its gold sizes,
blue usernames and status glyphs into one flat cream. Table cursors now
tint the background only, over a warm oxide wash instead of neutral.

Browse files, their sizes and the settings popup rendered in the raw
terminal foreground; they take the palette now, and free slots read
green when a peer has one.

soulseek-rs/src/ui/panes/download_info_pane.rs

@@ -199,12 +199,16 @@ fn build_info_lines(
             lines.push(label_value("Queue position", &position_text));
 
             if let Some(slots) = download.metadata.peer_free_slots {
-                let slot_text = if slots > 0 {
-                    format!("{slots} available")
+                let (slot_text, slot_style) = if slots > 0 {
+                    (format!("{slots} available"), success_style())
                 } else {
-                    "all busy".to_string()
+                    ("all busy".to_string(), inactive_style())
                 };
-                lines.push(label_value("Free slots", &slot_text));
+                lines.push(label_value_styled(
+                    "Free slots",
+                    slot_text,
+                    slot_style,
+                ));
             }
 
             if let Some(speed) = download.metadata.peer_upload_speed {