feat(ui): add press-to-capture shortcut editing to Keyboard Shortcuts dialog

Replace manual key entry with per-row capture cells: clicking + Add
inserts a draft row at the top with its key cell armed, and the next
key combination is recorded and normalized (Ctrl+Shift+S →
CTRL+SHIFT+S). While armed, a dedicated keyboard listener swallows all
input so recorded shortcuts do not execute in the drawing.

Draft rows are transient and confirmed only through an explicit accept
button, so the table never retains empty rows. Duplicate keys and
unrunnable commands are flagged in danger styling with a persistent
warning naming the conflicting command. Added reset-to-defaults with
confirmation, apply-and-exit, a shortcut count, and an unsaved-changes
guard on close.

src/app/view/mod.rs

@@ -118,6 +118,36 @@ fn hatch_pattern_key_event(
     }
 }
 
+fn shortcut_capture_key_event(
+    event: iced::Event,
+    _status: iced::event::Status,
+    _window: window::Id,
+) -> Option<Message> {
+    let iced::Event::Keyboard(keyboard::Event::KeyPressed { key, modifiers, .. }) = event else {
+        return None;
+    };
+    // Ignore bare modifier presses so holding Ctrl+Shift before the final
+    // key doesn't end the capture early.
+    if let keyboard::Key::Named(named) = &key {
+        if matches!(
+            named,
+            keyboard::key::Named::Control
+                | keyboard::key::Named::Shift
+                | keyboard::key::Named::Alt
+                | keyboard::key::Named::Super
+                | keyboard::key::Named::Meta
+        ) {
+            return None;
+        }
+    }
+    // Esc backs out of capture (and abandons an unfinished draft row) —
+    // binding the ESCAPE key itself is still possible via SHORTCUTS SET.
+    if matches!(key, keyboard::Key::Named(keyboard::key::Named::Escape)) {
+        return Some(Message::ShortcutCaptureCancel);
+    }
+    shortcut_key_name(&key, modifiers).map(Message::ShortcutCaptureKey)
+}
+
 fn shortcut_key_name(key: &keyboard::Key, modifiers: keyboard::Modifiers) -> Option<String> {
     let key = match key {
         keyboard::Key::Character(value) if !value.is_empty() => value.to_uppercase(),
@@ -2198,19 +2228,12 @@ impl OpenCADStudio {
         } else {
             Subscription::none()
         };
-        iced::Subscription::batch([
-            frames,
-            history_tick,
-            grip_dwell,
-            hover_dwell,
-            nav_settle,
-            thumbnail_capture,
-            caret_blink,
-            web_fonts,
-            autosave,
-            plugin_drain,
-            single_instance,
-            hatch_pattern_keys,
+        // While a shortcut-editor Key cell is armed for capture, a dedicated
+        // listener records the pressed combination and swallows every other
+        // key so captured shortcuts do not run in the drawing.
+        let keyboard_events = if self.shortcut_capture_row.is_some() {
+            event::listen_with(shortcut_capture_key_event)
+        } else {
             event::listen_with(|ev, status, win_id| {
                 use iced::event::Status;
                 match ev {
@@ -2340,7 +2363,22 @@ impl OpenCADStudio {
                     }
                     _ => None,
                 }
-            }),
+            })
+        };
+        iced::Subscription::batch([
+            frames,
+            history_tick,
+            grip_dwell,
+            hover_dwell,
+            nav_settle,
+            thumbnail_capture,
+            caret_blink,
+            web_fonts,
+            autosave,
+            plugin_drain,
+            single_instance,
+            hatch_pattern_keys,
+            keyboard_events,
         ])
     }