CDSL Bridge: Flange

Use for a circular flange, flanged sleeve, or coupling flange with a shared central axis.
Invariants: coaxial outside diameter, bore/hub, sealing land, and fastener holes on a pitch circle.
Plan: revolve_add for stepped axisymmetric bodies or circular extrude_add_blind -> coaxial bore -> one bolt-hole definition -> explicit circle set or supported repetition -> late finishing.
No circular-pattern atomic exists. Express a bolt circle with explicit circles in one cut profile when the engine schema supports that profile.
Keep bolt-circle diameter, count, start angle, bore, and hub dimensions distinct.