fix(brain): enforce r_f=6mm minimum, reject pockets that can't fit fillets

- Default r_f raised from 1.5mm to 6mm (machining constraint)
- Default min_pocket_radius raised to 6mm
- Pockets that can't fit r_f at any corner (within 80% tolerance) are
  skipped entirely — left solid for more stiffness in tight areas
- Result: 26 pockets (was 432), 187 NX entities (was 13,061)
- Min fillet radius: 4.88mm, all >= 4.8mm (80% of 6mm)
- Mass: 4,601g (was 3,480g — more solid = heavier but manufacturable)

tools/adaptive-isogrid/src/brain/pocket_profiles.py

@@ -136,11 +136,13 @@ def _fillet_corner(
         np.linalg.norm(v_next - v_corner) * 0.45,
     )
     if tan_dist > max_dist:
-        # Reduce fillet radius to fit
-        r_f = max_dist * np.tan(half_angle)
-        tan_dist = max_dist
-        if r_f < 0.05:
+        # Reduce fillet to fit, but never below hard minimum
+        r_f_reduced = max_dist * np.tan(half_angle)
+        if r_f_reduced < r_f * 0.8:
+            # Too much reduction — reject this corner
             return None
+        r_f = r_f_reduced
+        tan_dist = max_dist
 
     tangent_start = v_corner + d1 * tan_dist
     tangent_end = v_corner + d2 * tan_dist
@@ -180,6 +182,9 @@ def _compute_filleted_pocket(inset_verts: List[np.ndarray], r_f: float) -> Optio
         v_corner = inset_verts[i]
         v_next = inset_verts[(i + 1) % n]
         fillet = _fillet_corner(v_prev, v_corner, v_next, r_f)
+        if fillet is None and r_f > 0:
+            # Fillet doesn't fit at this corner — reject entire pocket
+            return None
         fillets.append(fillet)
 
     # Build lines connecting fillet tangent points
@@ -324,13 +329,15 @@ def generate_pockets(triangulation, geometry, params):
         if perimeter < 1e-6:
             continue
         inscribed_r = inset_area / (perimeter / 2.0)
-        if inscribed_r < min_pocket_radius:
+
+        # Pocket must be large enough to fit the required fillet radius.
+        # If inscribed_r < r_f, the fillet would dominate the pocket and
+        # create tiny/degenerate geometry. Skip these — leave them solid.
+        if inscribed_r < r_f:
             continue
 
-        # Compute fillet amount (don't over-fillet)
-        fillet_amount = min(r_f, inscribed_r * 0.4)
-        if fillet_amount < 0.1:
-            fillet_amount = 0.0
+        # Use full fillet radius — we've already verified it fits
+        fillet_amount = r_f
 
         pocket_geom = _compute_filleted_pocket(inset, fillet_amount)
         if pocket_geom is None: