fix(render): UTM-precise UCS icon + fallback outlines (hatch etc.)

Two UTM-scale rendering defects.

- UCS icon jittered: it projects only axis DIRECTIONS but went through the
  full view_proj, whose ~5.7e6 translation cancels catastrophically in f32.
  Feed it the rotation-only view_proj_rte instead (translation dropped).

- Fallback outline geometry (hatch boundary, viewport/insert/ole2frame
  frames, Solid3D edge wires) built absolute f32 points with an empty
  points_low, so at UTM the outline sat ~0.5 m off its own fill (the hatch
  fill renders precisely via the world_origin-relative HatchModel pipeline).
  FallbackGeometry now carries absolute f64 points + key vertices; the
  tessellate dispatcher splits them into the double-single high/low pair the
  relative-to-eye wire pass needs, so outlines land exactly on their fills.

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

src/entities/insert.rs

@@ -104,17 +104,18 @@ impl crate::entities::traits::FallbackTess for Insert {
         world_offset: [f64; 3],
     ) -> crate::scene::convert::tess_util::FallbackGeometry {
         let [ox, oy, oz] = world_offset;
-        let ip = Vec3::new(
-            (self.insert_point.x - ox) as f32,
-            (self.insert_point.y - oy) as f32,
-            (self.insert_point.z - oz) as f32,
+        let (ipx, ipy, ipz) = (
+            self.insert_point.x - ox,
+            self.insert_point.y - oy,
+            self.insert_point.z - oz,
         );
-        let s = 0.1_f32;
+        let ip = Vec3::new(ipx as f32, ipy as f32, ipz as f32);
+        let s = 0.1_f64;
         let pts = vec![
-            [ip.x - s, ip.y, ip.z],
-            [ip.x + s, ip.y, ip.z],
-            [ip.x, ip.y - s, ip.z],
-            [ip.x, ip.y + s, ip.z],
+            [ipx - s, ipy, ipz],
+            [ipx + s, ipy, ipz],
+            [ipx, ipy - s, ipz],
+            [ipx, ipy + s, ipz],
         ];
         (
             pts,