P1 (2/n): runners and example use the level-list constructor

run_refined_dfg, run_dfg_re20, time_window_dfg, time_refined_dfg,
run_jet_circle_cv and examples/fixed_patch_circle pass refinements /
level_blocks / level_objects / level_jets instead of bounds, base_block,
fine_block, fine_objects and jets. One-to-one with _legacy_levels: same
rectangle (FixedPatch2D frame), same blocks, bodies and Jets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/fixed_patch_circle.py

@@ -90,8 +90,8 @@ def main():
     # The caller owns the CUDA context; the stepper must be closed first (the
     # nested with-statement does that).
     with CudaContext(0) as context, FixedPatchStepper(
-            cfg, BOUNDS, context=context, coarse_boundary=args.mode,
-            fine_objects=[body], fine_block=fine_block) as run:
+            cfg, context=context, coarse_boundary=args.mode, refinements=[BOUNDS],
+            level_blocks=[None, fine_block], level_objects=[(), (body,)]) as run:
         p = run.patch
         # Rest equilibrium is already postcollision G, so no initial collision is
         # needed. Non-leaf entries (covered, ghost, solid) are discarded by initialize.