- ExceptionStack: init with base slot instead of empty vec
- with_frame_impl: save/restore exc_info value instead of
  push/pop slot, so callees see caller's handled exception
- Remove unused with_frame_exc
- resume_gen_frame: use push_exception/pop_exception methods
- codegen: move RERAISE inside cleanup handler's exception
  table range in finally blocks (both try-finally and
  try-except-finally), so POP_EXCEPT runs before re-raising

- Add eliminate_dead_stores pass before peephole_optimize:
  consecutive STORE_FAST to the same variable are replaced
  with POP_TOP (apply_static_swaps from CPython flowgraph.c)
- Remove 3 expectedFailure decorators in test_peepholer
  (test_load_fast_unknown_* now pass)
- Accept updated async_with snapshot
- Fix formatting in ir.rs, mod.rs, Python scripts