feat: right-click context menu + CONSTRUCTIONLINE alias

Viewport right-click now shows a proper widget-based context menu:
- When a command is active: Cancel / Enter
- Otherwise: Repeat last commands, Delete/Move/Copy (if selected),
  Select All, Zoom Extents

CONSTRUCTIONLINE added as an alias for XLINE (XL).
Canvas-drawn placeholder removed; context menu closes on Escape,
click-outside, or when any action is taken.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ui/command_line.rs

@@ -17,7 +17,7 @@ pub struct CommandLine {
     pub input: String,
     pub history: Vec<HistoryEntry>,
     /// Commands the user has typed (for ↑/↓ recall).
-    cmd_recall: Vec<String>,
+    pub cmd_recall: Vec<String>,
     /// Current position in `cmd_recall` while navigating (None = not navigating).
     recall_cursor: Option<usize>,
     /// Saved draft input before the user started navigating history.

src/ui/overlay.rs

@@ -385,49 +385,6 @@ impl canvas::Program<Message> for SelectionCanvas {
             }
         }
 
-        if let Some(p) = self.selection.context_menu {
-            let w = 140.0;
-            let h = 72.0;
-            let rect = canvas::Path::rectangle(Point::new(p.x, p.y), Size::new(w, h));
-            frame.fill(
-                &rect,
-                Color {
-                    r: 0.12,
-                    g: 0.12,
-                    b: 0.12,
-                    a: 0.95,
-                },
-            );
-            frame.stroke(
-                &rect,
-                canvas::Stroke {
-                    width: 1.0,
-                    style: canvas::Style::Solid(Color {
-                        r: 0.30,
-                        g: 0.30,
-                        b: 0.30,
-                        a: 1.0,
-                    }),
-                    ..Default::default()
-                },
-            );
-            let items = ["Open", "Properties", "Hide"];
-            for (i, item) in items.iter().enumerate() {
-                frame.fill_text(canvas::Text {
-                    content: item.to_string(),
-                    position: Point::new(p.x + 10.0, p.y + 10.0 + i as f32 * 20.0),
-                    color: Color::WHITE,
-                    size: iced::Pixels(11.0),
-                    font: iced::Font::DEFAULT,
-                    align_x: iced::alignment::Horizontal::Left.into(),
-                    align_y: iced::alignment::Vertical::Top.into(),
-                    max_width: f32::INFINITY,
-                    line_height: iced::widget::text::LineHeight::default(),
-                    shaping: iced::widget::text::Shaping::default(),
-                });
-            }
-        }
-
         // ── Grip markers ──────────────────────────────────────────────────
         for grip in &self.grips {
             let sp = grip.pos;