tune(brain): uniform triangulation + bigger spacing for r_f=6mm fillets

- Switched to uniform triangulation (no density-adaptive refinement for
  initial pass — saves that for stress-informed iterations)
- s_min=45mm, s_max=55mm (was 12/35) — larger triangles fit 6mm fillets
- Boss keepout circles: 12 segments (was 32) — less boundary clutter
- Fillet must be >= 80% of r_f at every corner or pocket is skipped
- Result: 75 pockets, 481 NX entities, min fillet 4.85mm, mass 4066g
- adaptive_density=True param enables density refinement for future stress iterations

tools/adaptive-isogrid/src/atomizer_study.py

@@ -37,8 +37,8 @@ DEFAULT_PARAMS = {
     'p': 2.0,
     'beta': 0.3,
     'R_edge': 15.0,
-    's_min': 12.0,
-    's_max': 35.0,
+    's_min': 45.0,
+    's_max': 55.0,
     't_min': 2.5,
     't_0': 3.0,
     'gamma': 1.0,