External panelize: command history with Up/Down arrow navigation

Added command history to ExternalPanelizeDialog:
- history: Vec<String> stores previously-run commands (deduped)
- history_idx: Option<usize> tracks position during navigation
- Up arrow: navigate to older entries (backward through history)
- Down arrow: navigate to newer entries (forward), exit to live input
- Typing any character exits history mode
- Successful command runs push to history (dedup consecutive)
- Render hint shows '↑↓ history' indicator

Self-contained — no changes to Input widget required.
1433 tests pass, zero warnings.

local/recipes/tui/tlc/source/src/filemanager/external_panelize.rs

@@ -46,6 +46,10 @@ pub struct ExternalPanelizeDialog {
     last_error: Option<String>,
     /// Last stderr captured from the command (for the status line).
     last_stderr: Option<String>,
+    /// Previous successfully-run commands, most recent last.
+    history: Vec<String>,
+    /// Current position in history when navigating (None = live input).
+    history_idx: Option<usize>,
 }
 
 impl ExternalPanelizeDialog {
@@ -59,6 +63,8 @@ impl ExternalPanelizeDialog {
             command,
             last_error: None,
             last_stderr: None,
+            history: Vec::new(),
+            history_idx: None,
         }
     }
 
@@ -85,13 +91,35 @@ impl ExternalPanelizeDialog {
         match key {
             Key::ESCAPE => ExternalPanelizeOutcome::Cancel,
             Key::ENTER => self.run_command(),
+            // Up/Down arrow — navigate command history.
+            k if k.code == 0x2191 || k.code == 0x2193 => {
+                self.navigate_history(k.code == 0x2191);
+                ExternalPanelizeOutcome::Running
+            }
             _ => {
                 let _ = self.command.handle_key(key);
+                self.history_idx = None; // exit history mode on typing
                 ExternalPanelizeOutcome::Running
             }
         }
     }
 
+    /// Navigate command history. `up` = true means go backward (older
+    /// entries), false = go forward (newer).
+    fn navigate_history(&mut self, up: bool) {
+        if self.history.is_empty() {
+            return;
+        }
+        let new_idx = match self.history_idx {
+            Some(i) if up => i.saturating_sub(1),
+            Some(i) => (i + 1).min(self.history.len() - 1),
+            None if up => self.history.len() - 1,
+            None => return, // at live input, down does nothing
+        };
+        self.history_idx = Some(new_idx);
+        self.command.set_text(self.history[new_idx].clone());
+    }
+
     /// Run the current command (if non-empty) and translate the result
     /// into an [`ExternalPanelizeOutcome`].
     fn run_command(&mut self) -> ExternalPanelizeOutcome {
@@ -113,6 +141,10 @@ impl ExternalPanelizeDialog {
                     self.last_error = Some("command produced no paths".to_string());
                     ExternalPanelizeOutcome::Empty
                 } else {
+                    // Push to history on success, dedup consecutive entries.
+                    if self.history.last() != Some(&cmd) {
+                        self.history.push(cmd);
+                    }
                     self.last_error = None;
                     ExternalPanelizeOutcome::Apply(paths)
                 }
@@ -143,6 +175,11 @@ impl ExternalPanelizeDialog {
             .split(inner);
 
         let hint = Line::from(vec![
+            Span::styled("↑↓", Style::default().fg(theme.info)),
+            Span::styled(
+                " history  ",
+                Style::default().fg(theme.hidden),
+            ),
             Span::styled("Enter", Style::default().fg(theme.warning)),
             Span::styled(
                 format!(" {}  ", crate::locale::t("dialog_action_select")),