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 <[email protected]>

src/command.rs

@@ -28,9 +28,9 @@ pub enum EntityTransform {
     /// Move every point by the given world-space delta (world XY plane).
     Translate(DVec3),
     /// Rotate around `center` by `angle_rad` in the world XY plane.
-    Rotate { center: DVec3, angle_rad: f32 },
+    Rotate { center: DVec3, angle_rad: f64 },
     /// Uniform scale from `center` by `factor`.
-    Scale { center: DVec3, factor: f32 },
+    Scale { center: DVec3, factor: f64 },
     /// Mirror across the line through `p1`→`p2` in the world XY plane.
     Mirror { p1: DVec3, p2: DVec3 },
 }
@@ -236,8 +236,8 @@ pub enum CmdResult {
         handles: Vec<Handle>,
         src1: DVec3,
         dst1: DVec3,
-        angle_rad: f32,
-        scale: f32,
+        angle_rad: f64,
+        scale: f64,
     },
     /// Set the plot window on the active layout's PlotSettings.
     SetPlotWindow { p1: DVec3, p2: DVec3 },
@@ -291,7 +291,7 @@ pub enum CmdResult {
     /// Extrude the profile entity `handle` by `height` along Z.
     ExtrudeEntity {
         handle: Handle,
-        height: f32,
+        height: f64,
         color: [f32; 4],
     },
     /// Revolve the profile entity `handle` around the given axis by `angle_deg`.