feat(layers): draggable Name-column width in the Layer Manager (#359)

A thin divider after the Name header resizes the column by drag
(60-640 px, session-persistent), riding the shared modal drag flow.
The name elide budget follows the column width, so widening the
column reveals long layer names; the hover tooltip stays for overflow.

Co-Authored-By: Claude Fable 5 <[email protected]>

src/app/mod.rs

@@ -461,6 +461,11 @@ pub(super) struct OpenCADStudio {
     modal_drag_last: Option<Point>,
     /// True while the modal title bar is held (a drag is in progress).
     modal_dragging: bool,
+    /// Layer Manager: dragging the Name-column divider (width follows the
+    /// shared ModalDragMove flow).
+    layer_col_dragging: bool,
+    /// Layer Manager Name column width in px, adjusted by the divider drag.
+    layer_name_col_w: f32,
     /// How far the user has dragged the modal's corner resize grip from the
     /// dialog's natural size (added to each modal's default width/height). Reset
     /// with `modal_offset` so every dialog opens at its own size.
@@ -1364,6 +1369,8 @@ pub enum Message {
     CommandHistoryNext,
     /// Toggle the dropdown listing the full command-line history.
     CommandHistoryToggle,
+    /// Start dragging the Layer Manager's Name-column divider.
+    LayerNameColGrab,
     /// Toggle the persistent literal-space mode (the `>` button): while on,
     /// every command line behaves as if it started with `>` — Space stays in
     /// the input instead of submitting. Saved in the user config.
@@ -2286,6 +2293,8 @@ impl OpenCADStudio {
             modal_offset: iced::Vector::ZERO,
             modal_drag_last: None,
             modal_dragging: false,
+            layer_col_dragging: false,
+            layer_name_col_w: 130.0,
             modal_resize: iced::Vector::ZERO,
             modal_resizing: false,
             attr_editor_handle: None,

src/app/update/mod.rs

@@ -3246,10 +3246,18 @@ impl OpenCADStudio {
                 self.modal_drag_last = None;
                 Task::none()
             }
+            Message::LayerNameColGrab => {
+                // Start a Name-column divider drag; rides ModalDragMove.
+                self.layer_col_dragging = true;
+                self.modal_drag_last = None;
+                Task::none()
+            }
             Message::ModalDragMove(p) => {
                 if let Some(last) = self.modal_drag_last {
                     let (dx, dy) = (p.x - last.x, p.y - last.y);
-                    if self.modal_resizing {
+                    if self.layer_col_dragging {
+                        self.layer_name_col_w = (self.layer_name_col_w + dx).clamp(60.0, 640.0);
+                    } else if self.modal_resizing {
                         // The grip sits bottom-right, so dragging out grows the
                         // box. The delta is added to each dialog's natural size,
                         // so clamp it at zero — dragging in past the natural size
@@ -3280,7 +3288,7 @@ impl OpenCADStudio {
                         }
                     }
                 }
-                if self.modal_dragging || self.modal_resizing {
+                if self.modal_dragging || self.modal_resizing || self.layer_col_dragging {
                     self.modal_drag_last = Some(p);
                 }
                 Task::none()
@@ -3288,6 +3296,7 @@ impl OpenCADStudio {
             Message::ModalDragRelease => {
                 self.modal_dragging = false;
                 self.modal_resizing = false;
+                self.layer_col_dragging = false;
                 self.modal_drag_last = None;
                 Task::none()
             }

src/app/view/modal.rs

@@ -81,7 +81,7 @@ impl OpenCADStudio {
             }
             super::super::ModalKind::Layers => {
                 let tab = &self.tabs[self.active_tab];
-                sized(tab.layers.view_window(), 900, 360)
+                sized(tab.layers.view_window(self.layer_name_col_w), 900, 360)
             }
             super::super::ModalKind::Plot => {
                 sized(crate::ui::window::plot::view_window(&self.plot_dialog), 760, 540)