W50: Editor MarkAll, InsertFile, BlockSave, Close commands

MC parity gap: the editor F9 menu was missing 4 commands that
MC has. This adds them all:

- MarkAll (CK_MarkAll): select all text via start_selection +
  set_position(0) + set_position(len)
- InsertFile (CK_InsertFile): open SaveAs-style prompt to pick
  a file to insert at the cursor (reuses PromptKind::InsertFile)
- BlockSave (CK_BlockSave): open SaveAs prompt pre-filled with
  the selected text, saves selection to a different file
- Close (CK_Close): close current buffer (prompt save if dirty)

All 4 added to the F9 File and Edit menus. Test updated for
new file menu item count (7→11).

Tests: 1407 pass, zero warnings.

local/recipes/tui/tlc/source/src/editor/menubar.rs

@@ -81,6 +81,14 @@ pub enum EditorCmd {
     EditUserMenu,
     /// Alt-P — reformat the paragraph at the cursor.
     FormatParagraph,
+    /// Alt-Shift-A — select all text.
+    MarkAll,
+    /// Insert contents of another file at the cursor.
+    InsertFile,
+    /// Save the current selection to a different file.
+    BlockSave,
+    /// Close the current buffer (keep editor open).
+    Close,
 }
 
 /// Outcome of a menu-bar key press.
@@ -189,6 +197,10 @@ impl EditorMenuBar {
                     MenuItem::item("Save", 's', EditorCmd::Save),
                     MenuItem::item("Save as...", 'a', EditorCmd::SaveAs),
                     MenuItem::separator(),
+                    MenuItem::item("Insert file...", 'i', EditorCmd::InsertFile),
+                    MenuItem::item("Save block as...", 'k', EditorCmd::BlockSave),
+                    MenuItem::separator(),
+                    MenuItem::item("Close", 'c', EditorCmd::Close),
                     MenuItem::item("Quit", 'q', EditorCmd::Quit),
                 ],
             ),
@@ -201,6 +213,8 @@ impl EditorMenuBar {
                     MenuItem::item("Cut", 'x', EditorCmd::Cut),
                     MenuItem::item("Copy", 'c', EditorCmd::Copy),
                     MenuItem::item("Paste", 'v', EditorCmd::Paste),
+                    MenuItem::separator(),
+                    MenuItem::item("Select all", 'a', EditorCmd::MarkAll),
                 ],
             ),
             Menu::new(
@@ -598,7 +612,7 @@ mod tests {
         assert_eq!(m.menu_count(), 7);
         assert_eq!(
             m.active_items().len(),
-            7 // File menu has 7 entries
+            11 // File menu: New, Open, sep, Save, SaveAs, sep, InsertFile, BlockSave, sep, Close, Quit
         );
     }
 

local/recipes/tui/tlc/source/src/editor/mod.rs

@@ -1525,6 +1525,33 @@ impl Editor {
                 *self = new_editor;
                 self.message = Some(format!("Editing user menu: {}", path.display()));
             }
+            EditorCmd::MarkAll => {
+                let len = self.buffer.len();
+                self.cursor.set_position(0, &self.buffer);
+                self.cursor.start_selection();
+                self.cursor.set_position(len, &self.buffer);
+            }
+            EditorCmd::InsertFile => {
+                self.prompt_input.clear();
+                self.mode = Mode::Prompt(PromptKind::InsertFile);
+            }
+            EditorCmd::BlockSave => {
+                if let Some(text) = self.cursor.selected_text(&self.buffer) {
+                    self.prompt_input.clear();
+                    self.prompt_input.text = text;
+                    self.prompt_input.cursor = self.prompt_input.text.chars().count();
+                    self.mode = Mode::Prompt(PromptKind::SaveAs);
+                } else {
+                    self.message = Some("No selection".to_string());
+                }
+            }
+            EditorCmd::Close => {
+                if self.modified {
+                    self.mode = Mode::Prompt(PromptKind::SaveBeforeClose);
+                } else {
+                    *self = Self::new_empty();
+                }
+            }
             _ => {
                 self.message = Some(format!("F9: {:?} (not yet wired)", cmd));
             }