CAM: Improve Z retract reliability in rotational scan after geometry recompute

Introduced FLOAT_EPSILON for robust floating point comparisons, resolving cases
where Z axis retract moves were missing after geometry recompute in 3D Surface
rotational scan operations. This prevents precision errors from causing the
cutter to skip intended lifts between rings or scan lines.

src/Mod/CAM/Path/Op/Surface.py
 - Added FLOAT_EPSILON constant
 - Updated Z move comparison logic to use tolerance

src/Mod/CAM/Path/Op/Surface.py

@@ -68,6 +68,8 @@ if False:
 else:
     Path.Log.setLevel(Path.Log.Level.INFO, Path.Log.thisModule())
 
+FLOAT_EPSILON = 1e-6  # Small value for floating point comparisons
+
 
 class ObjectSurface(PathOp.ObjectOp):
     """Proxy object for Surfacing operation."""
@@ -2162,7 +2164,6 @@ class ObjectSurface(PathOp.ObjectOp):
             if (
                 obj.RotationAxis == obj.DropCutterDir
             ):  # Same == indexed (cutter runs parallel to axis)
-
                 # Translate scan to gcode
                 sumAdv = begIdx
                 for sl in range(0, len(scanLines)):
@@ -2424,7 +2425,7 @@ class ObjectSurface(PathOp.ObjectOp):
         # Adjust feed rate based on radius/circumference of cutter.
         # Original feed rate based on travel at circumference.
         if rN > 0:
-            if pnt.z >= self.layerEndzMax:
+            if pnt.z >= self.layerEndzMax - FLOAT_EPSILON:
                 clrZ = pnt.z + 5.0
                 output.append(Path.Command("G1", {"Z": clrZ, "F": self.vertRapid}))
         else: