V57 FLAT FINITE-FAULT STAMP PATCHES

What changed
- Keeps V56 reverse/normal branched secondary deformation.
- Changes direct finite-fault stamp patches from raised-cosine/Gaussian-like amplitude to constant-slip tiles.

Why
- In V55/V56, a single clicked/imported patch had strong internal amplitude falloff from the center to the edge.
- When many finite-fault patches were stamped, this created speckled green/yellow variations inside what should visually behave like one subfault tile.
- Finite-fault models normally treat each subfault tile as approximately uniform slip, so the direct patch should not have a Gaussian profile inside itself.

Result
- Each finite-fault stamp patch should look much flatter internally.
- Patch-to-patch differences still remain if the imported/selected slip differs between patches.
- Secondary deformation is still generated from the reconstructed brush-like mask.

Operational notes
- Use this over V55/V56 if the direct stamped fault area looks noisy or Gaussian within each small patch.
- Press G to regenerate secondary deformation after editing the finite-fault model.
