fix(wipeout): frame draws above the mask; mask joins the draw order

The wipeout pass ran after the wire pass with no draw-order bias, so
the mask erased its own boundary frame (and everything else at its
plane regardless of draw order). The mask uniform now carries the
entity's draw-order depth (uniform grows 80 → 96 bytes) and biases its
clip-z like every other pipeline, and the frame wire rides a
+half-rank override — the later mask pass fails the depth test at the
frame's pixels, so the boundary stays visible, while entities drawn
above the wipeout are no longer erased.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scene/pipeline/wipeout_gpu.rs

@@ -47,7 +47,7 @@ impl HatchVertex {
 
 // ── Uniform structs ───────────────────────────────────────────────────────
 
-/// Per-hatch parameters (binding 0).  Must be 80 bytes (16-byte aligned).
+/// Per-hatch parameters (binding 0).  Must be 96 bytes (16-byte aligned).
 ///
 /// `mode` encoding:
 ///   0 → Pattern  (families in FamilyBatchData)
@@ -75,7 +75,9 @@ pub struct HatchUniformData {
     //                       //     is small (e.g. UTM drawing + sub-mm hatch).
     pub origin_low: [f32; 2], // 72: anchor low residual (double-single) so the
     //                        //     vertex clip position stays precise at UTM scale.
-} // total 80 bytes
+    pub draw_depth: f32,      // 80: signed (-1,1) draw-order bias
+    pub _pad: [f32; 3],       // 84..96
+} // total 96 bytes
 
 /// Boundary polygon (binding 1).  Matches WGSL `Boundary`.
 #[repr(C)]
@@ -298,6 +300,8 @@ impl WipeoutGpu {
                 (origin[0] - origin[0] as f32 as f64) as f32,
                 (origin[1] - origin[1] as f32 as f64) as f32,
             ],
+            draw_depth: model.draw_depth,
+            _pad: [0.0; 3],
         };
 
         // ── BoundaryData (in snapped-local space) ────────────────────────