feat(commands): integrate standard CAD commands and fix behavior gaps

Broad pass over the command set: integrate missing commands, wire
previously-unreachable ribbon/menu buttons, and correct name/behaviour
mismatches. Every UI command token now resolves (real handler where the
infrastructure exists, an honest "not yet implemented" status otherwise).

New commands:
- Draw: 3DPOLY, 2D solid (SO/SOLID2D), HELIX, TRACE, SKETCH, DIMCENTER
  (DCE/CENTERMARK)
- Modify/inquiry: REVERSE, MEASUREGEOM (MEA), DBLIST
- Data/manage: BASE, OVERKILL (exact-duplicate removal), AUDIT (read-only
  integrity report), SETVAR (system-variable get/set), SCRIPT (.scr runner),
  FINDNONPURGEABLE

Behaviour fixes:
- LINE and SPLINE gain Close/Undo; AREA computes area/perimeter in f64
  (correct at large coordinates)
- ATTEDIT/ATE unified so the alias and the ribbon button open the
  interactive editor; -ATTEDIT is the command-line form
- Linear/aligned/radius/diameter dimensions gain a text override (Text) and
  text angle (Angle) option
- INSERT gains Scale/Rotate options; COPY gains an Array option
- LINETYPE SET sets the current entity linetype; SETBYLAYER resets overrides
- UNDO accepts a step count

Integrations: standard dimension/block aliases (DLI/DRA/DAN, BMAKE,
EXPORTPDF, DDIM), drafting-aid and screen toggles (GRID/SNAP/POLAR/OSNAP/
DSETTINGS/CLEANSCREEN/QUICKPROPERTIES), viewport tiling
(CASCADE/HORIZONTAL/VERTICAL/VPJOIN), and customization entry points
(CUI/ALIASEDIT).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/modules/draw/inquiry/area.rs

@@ -1,13 +1,13 @@
 // AREA command — compute area and perimeter of a polygon picked point by point.
 // Press Enter to close and calculate.
 
-use glam::{DVec3, Vec3};
+use glam::DVec3;
 
 use crate::command::{CadCommand, CmdResult};
 use crate::scene::model::wire_model::WireModel;
 
 pub struct AreaCommand {
-    points: Vec<Vec3>,
+    points: Vec<DVec3>,
 }
 
 impl AreaCommand {
@@ -32,7 +32,7 @@ impl CadCommand for AreaCommand {
         }
     }
 
-    fn on_point(&mut self, pt: DVec3) -> CmdResult { let pt = pt.as_vec3();
+    fn on_point(&mut self, pt: DVec3) -> CmdResult {
         self.points.push(pt);
         CmdResult::NeedPoint
     }
@@ -41,28 +41,33 @@ impl CadCommand for AreaCommand {
         if self.points.len() < 3 {
             return CmdResult::Cancel;
         }
-        // Shoelace formula in the world XY plane.
+        // Shoelace formula in the world XY plane, evaluated in f64 relative to
+        // the first vertex. Subtracting that origin keeps the cross-product
+        // terms small even at large (survey/UTM) coordinates, avoiding the
+        // catastrophic cancellation a raw f32/absolute evaluation suffers.
         let n = self.points.len();
-        let mut area_sum = 0.0f32;
-        let mut perimeter = 0.0f32;
+        let origin = self.points[0];
+        let mut area_sum = 0.0f64;
+        let mut perimeter = 0.0f64;
         for idx in 0..n {
-            let a = self.points[idx];
-            let b = self.points[(idx + 1) % n];
+            let a = self.points[idx] - origin;
+            let b = self.points[(idx + 1) % n] - origin;
             area_sum += a.x * b.y - b.x * a.y;
-            perimeter += (b - a).length();
+            perimeter += (self.points[(idx + 1) % n] - self.points[idx]).length();
         }
         let area = (area_sum * 0.5).abs();
         let msg = format!("Area = {area:.4},  Perimeter = {perimeter:.4}");
         CmdResult::Measurement(msg)
     }
 
-    fn on_mouse_move(&mut self, pt: DVec3) -> Option<WireModel> { let pt = pt.as_vec3();
+    fn on_mouse_move(&mut self, pt: DVec3) -> Option<WireModel> {
         if self.points.is_empty() {
             return None;
         }
-        let mut pts: Vec<[f32; 3]> = self.points.iter().map(|p| [p.x, p.y, p.z]).collect();
-        pts.push([pt.x, pt.y, pt.z]);
-        pts.push([self.points[0].x, self.points[0].y, self.points[0].z]);
+        let f = |p: DVec3| [p.x as f32, p.y as f32, p.z as f32];
+        let mut pts: Vec<[f32; 3]> = self.points.iter().map(|p| f(*p)).collect();
+        pts.push(f(pt));
+        pts.push(f(self.points[0]));
         Some(WireModel {
             name: "area_preview".into(),
             points: pts,