refactor(precision): widen command transform scalars and defaults to f64 (#311)

Completes the f64 migration on the CPU data path: the only f32 left now
is the GPU/render/screen layer, which is architecturally required (wgpu
vertex buffers and iced are f32; f64 vertices would double memory).

- EntityTransform::Rotate.angle_rad and Scale.factor are now f64 (the
  transform was already applied in f64 around the DVec3 center, so this
  only preserves the typed angle/factor). apply_standard_transform and
  apply_standard_scale take f64.
- CmdResult::ExtrudeEntity.height and AlignSelected.{angle_rad,scale}
  are f64; the EXTRUDE height parses as f64.
- defaults.rs (last-used construction values: circle radius/diameter,
  rotate angle, scale factor, offset/fillet/chamfer distance, array
  spacing/counts/angle) moved from Cell<f32> to Cell<f64>. Array counts
  round-trip through u32 (exact below 2^53).
- Consumers in circle/array/fillet/offset/rotate/scale/align/solid3d and
  dimension.rs rotate_point/scale_point follow. `as f32` is kept only
  where a value feeds a WireModel rubber-band/ghost (the preview path is
  screen-space f32).

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

src/modules/draw/modify/rotate.rs

@@ -37,7 +37,7 @@ pub struct RotateCommand {
     handles: Vec<Handle>,
     wire_models: Vec<WireModel>,
     step: Step,
-    default_angle: f32, // degrees
+    default_angle: f64, // degrees
 }
 
 impl RotateCommand {
@@ -90,13 +90,13 @@ impl CadCommand for RotateCommand {
                 let ref_angle = *ref_angle;
                 let dest_angle = (pt.y - center.y).atan2(pt.x - center.x);
                 let delta = dest_angle - ref_angle;
-                defaults::set_rotate_angle(delta.to_degrees() as f32);
-                self.default_angle = delta.to_degrees() as f32;
+                defaults::set_rotate_angle(delta.to_degrees());
+                self.default_angle = delta.to_degrees();
                 CmdResult::TransformSelected(
                     self.handles.clone(),
                     EntityTransform::Rotate {
                         center,
-                        angle_rad: delta as f32,
+                        angle_rad: delta,
                     },
                 )
             }
@@ -131,7 +131,7 @@ impl CadCommand for RotateCommand {
         };
         // The value already carries the correct sign (the dynamic-input
         // layer applies the cursor's side for a bare magnitude).
-        let deg: f32 = text.trim().replace(',', ".").parse().ok()?;
+        let deg: f64 = text.trim().replace(',', ".").parse().ok()?;
         defaults::set_rotate_angle(deg);
         Some(CmdResult::TransformSelected(
             self.handles.clone(),
@@ -165,7 +165,7 @@ impl CadCommand for RotateCommand {
         // committing with Enter rotates the way the cursor is dragging — the
         // dynamic-input box shows the unsigned magnitude, but the committed
         // value must keep its direction (clockwise = negative).
-        self.default_angle = angle_rad.to_degrees() as f32;
+        self.default_angle = angle_rad.to_degrees();
         // Object ghosts rotated to the new angle. The rotation sweep arc is
         // drawn by the dynamic-input overlay (polar guide), not here.
         self.wire_models