feat(f64): command layer compiles on DVec3

Whole command/snap/grip/cursor chain now builds on f64 DVec3 end to end,
so picked points, snaps and grip drags stay precise at UTM-scale
coordinates instead of quantizing to ~0.5 m through f32.

- All ~80 command files migrated: draw (line/circle/arc/ellipse/shapes
  in full f64; others via point methods), modify, annotate, insert, view,
  inquiry, layers, groups, clipboard, layout.
- Entity apply_grip impls updated for GripApply::{Absolute,Translate}(DVec3).
- Construction sites (EntityTransform/CmdResult/DynAnchor) emit DVec3;
  wire-preview boundaries cast to f32 only at the GPU edge.
- Modify/annotate commands keep internal Vec3 geometry where precision is
  non-critical, casting at the DVec3 boundary; key draw commands store f64.

Builds clean (no warnings). Visual verification of crosshair/snap/grip at
extreme UTM zoom pending.

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

src/modules/draw/clipboard/paste.rs

@@ -16,7 +16,7 @@ pub const MENU_ITEMS: &[(&str, &str, IconKind)] = &[
 // ── CadCommand implementation ─────────────────────────────────────────────
 
 use acadrust::Handle;
-use glam::Vec3;
+use glam::{DVec3, Vec3};
 
 use crate::command::{CadCommand, CmdResult};
 use crate::scene::model::wire_model::WireModel;
@@ -43,7 +43,7 @@ impl CadCommand for PasteCommand {
         "PASTECLIP  Pick insertion point:".into()
     }
 
-    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+    fn on_point(&mut self, pt: DVec3) -> CmdResult {
         CmdResult::PasteClipboard { base_pt: pt }
     }
 
@@ -51,11 +51,11 @@ impl CadCommand for PasteCommand {
         CmdResult::Cancel
     }
 
-    fn on_hover_entity(&mut self, _handle: Handle, _pt: Vec3) -> Vec<WireModel> {
+    fn on_hover_entity(&mut self, _handle: Handle, _pt: DVec3) -> Vec<WireModel> {
         vec![]
     }
 
-    fn on_preview_wires(&mut self, pt: Vec3) -> Vec<WireModel> {
+    fn on_preview_wires(&mut self, pt: DVec3) -> Vec<WireModel> { let pt = pt.as_vec3();
         let delta = pt - self.centroid;
         self.wires.iter().map(|w| w.translated(delta)).collect()
     }