fix(clothing): close the coverage holes, and bind materials without crashing

Solidify thickness went from 1 cm to 2 cm and the shell is fattened 8 mm along its own
normals afterwards. That closed the shoulders, hips and knees where the body was
showing through the cloth.

Evaluation against the blueprint, same shot and box before and after:
  mean deltaE     31.9 -> 21.8
  palette deltaE  25.4 -> 19.7
  aspect delta     1.24 -> 1.22

Also fixes a crash I introduced: binding the materials in Tick used
ConstructorHelpers::FObjectFinder, which is fatal outside a constructor - the game died
with 'FObjectFinders can't be used outside of constructors' and the render run failed
with signal 11. The binding now lives in BeginPlay and uses LoadObject.

Not fixed, and recorded: the arms and face still render neutral grey, so
M_Character_Skin itself is suspect rather than the assignment.

MEMORY.md

@@ -508,3 +508,5 @@ Scope: facts and traps that cost time to establish. Planned work lives in [TODO.
 - **MPFB vertex groups are polluted by helper geometry.** The body mesh weights its helper cubes to groups named `Left`, `Right`, `HelperGeometry` and `JointCubes` at 1.0, so a "strongest group" lookup returns a helper for most vertices - the first clothing build selected **zero** faces. Filter helper names out before asking which bone a vertex belongs to.
 - **Blender refuses to apply a modifier to a mesh with shape keys.** The body carries ten; a garment copy must clear them (`shape_key_remove(all=True)`) before solidify can be applied.
 - **Edit-mode selection reverts to vertex selection.** Setting `polygon.select` in object mode and then entering edit mode re-derives selection from the vertices, which were all still selected - deleting "the unselected faces" wiped the entire garment. Filter with `bmesh.ops.delete(context="FACES")` instead.
+- **`ConstructorHelpers::FObjectFinder` outside a constructor is a fatal error**, not a warning: the game dies in `Tick` with "FObjectFinders can't be used outside of constructors". Use `LoadObject<T>(nullptr, Path)` for runtime loads and keep `FObjectFinder` to the constructor.
+- **A 1 cm solidify shell lets the body poke through.** Garments built by duplicating body faces needed 2 cm of solidify plus an 8 mm fatten along their own normals before the cloth read as continuous at shoulders, hips and knees.