Booleans: when the last-resort nudge fails both ways, try two more screw axes (#1490) (#1527)

Thanks @erkexzcx.

tests/robustness/goldens.json

@@ -64,7 +64,7 @@
   "60": {"area":3443.328607,"bodies":1,"edges":39,"error":null,"faces":15,"outcome":"ok","rejected":0,"shells":1,"steps":["revolved section","cut sphere"],"unsupported":0,"volume":11779.204543},
   "61": {"area":5020.413153,"bodies":1,"edges":36,"error":"boolean Cut: the operation failed: no result","faces":15,"outcome":"failed","rejected":0,"shells":1,"steps":["extruded profile","cut cylinder","shell","rectangular pattern"],"unsupported":0,"volume":4906.628538},
   "62": {"area":8771.003732,"bodies":1,"edges":60,"error":null,"faces":23,"outcome":"ok","rejected":0,"shells":1,"steps":["extruded profile","cut cylinder","circular pattern","cut box","cut box","join cylinder"],"unsupported":2,"volume":40107.001728},
-  "63": {"area":3060.37707,"bodies":1,"edges":57,"error":"boolean Union: implausible result volume ","faces":21,"outcome":"failed","rejected":1,"shells":1,"steps":["revolved section","join box","cut cylinder","hole","cut cylinder","join box"],"unsupported":0,"volume":6534.395036},
+  "63": {"area":3198.797259,"bodies":1,"edges":84,"error":null,"faces":30,"outcome":"ok","rejected":1,"shells":1,"steps":["revolved section","join box","cut cylinder","hole","cut cylinder","join box","fillet"],"unsupported":0,"volume":7075.892751},
   "64": {"area":4088.335645,"bodies":1,"edges":36,"error":null,"faces":14,"outcome":"ok","rejected":0,"shells":1,"steps":["extruded profile","fillet","join cylinder"],"unsupported":0,"volume":8495.220295},
   "65": {"area":8442.175249,"bodies":1,"edges":33,"error":null,"faces":13,"outcome":"ok","rejected":0,"shells":1,"steps":["box","cut cylinder","fillet","rectangular pattern","circular pattern","circular pattern","fillet","cut box"],"unsupported":0,"volume":45117.305023},
   "66": {"area":9222.76638,"bodies":1,"edges":99,"error":null,"faces":37,"outcome":"ok","rejected":0,"shells":1,"steps":["extruded profile","join box","join box","join box","cut sphere","cut box"],"unsupported":1,"volume":35217.203139},
@@ -122,6 +122,7 @@
   {"reason":"#391 after merging main with #1213: seed 41 now reaches its second fillet (built since #1213), and the end-snap fix again drops a sliver edge the cuts left (94 to 93 edges); its steps, outcome, faces and shells are unchanged, volume moves by 0.005 mm³ (5185.215737 to 5185.221068) and area by 0.0014 mm²","seeds":[41]},
   {"reason":"the chamfer bug is on main too, see #1390","seeds":[57]},
   {"reason":"#1390: a chamfer of a convex edge that would grow the part is refused (TooLarge). Seed 57's 0.5 mm chamfer on the sphere cut's rim, which grew the part since #391 reordered its steps, is now refused, so the run goes on to its later steps and ends ok (16017.21 mm³, 24 faces)","seeds":[57]},
-  {"reason":"seed 15 now cuts around a sealed void","seeds":[15]}
+  {"reason":"seed 15 now cuts around a sealed void","seeds":[15]},
+  {"reason":"#1490: when the last-resort nudge fails both ways, two more screw axes are tried; seed 63's final box join (its face 0.00005 mm off the half-ring's cut face) now builds instead of being refused with an implausible volume, and the design goes on to its fillet","seeds":[63]}
  ]
 }