refactor(hatch): unify capability backends

Keep storage and texture transports behind one renderer lifecycle so Pipeline no longer branches by backend.

src/shaders/hatch.wgsl

@@ -5,7 +5,7 @@
 // positions so we don't depend on @builtin(instance_index) edge cases
 // across backends).
 //
-// Layout — matches `hatch_gpu.rs`:
+// Layout — matches `hatch_gpu/storage.rs`:
 //   group 1 binding 0  InstanceBuffer  HatchInstance[]   (128 B / inst)
 //   group 1 binding 1  BoundaryBuffer  vec4<f32>[]       (xy in .xy)
 //   group 1 binding 2  FamilyBuffer    LineFamilyGpu[]   (48 B / fam)

src/shaders/hatch_texture.wgsl

@@ -1,4 +1,4 @@
-// Hatch shader (WebGL2) — texture-backed, UNCAPPED variant of wipeout.wgsl.
+// Hatch texture shader — storage-free, UNCAPPED variant of wipeout.wgsl.
 //
 // Devices without vertex/fragment storage buffers cannot use the batched
 // storage-buffer renderer (hatch.wgsl). This shader keeps the exact