refactor: remove all backward-compat shims from sim/

Deletes 24 shim files from sim/. All test imports now point directly
to canonical transponders/ and trace/ paths. sim/ contains only
infrastructure (15 files): frame, memory, transponder ABC, reader ABC,
medium, sim_session, table_compiler, replay, relay, fuzzer, pm3medium,
mcu_bridge, mcu_protocol, dual_session, __init__.

751 tests passing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/test_sim_implants.py

@@ -3,12 +3,12 @@ import asyncio
 import pytest
 
 from pm3py.sim.medium import SoftwareMedium
-from pm3py.sim.implants import (
+from pm3py.transponders.implants import (
     xEM, xNT, xM1, FlexDF, NExT,
     MagicMifareClassicTag,
 )
-from pm3py.sim.em4100 import EM4100Reader
-from pm3py.sim.iso14443a import Reader14443A, _compute_bcc
+from pm3py.transponders.lf.em.em4100 import EM4100Reader
+from pm3py.transponders.hf.iso14443a.base import Reader14443A, _compute_bcc
 
 
 def run(coro):
@@ -36,7 +36,7 @@ class TestXNT:
         assert tag._total_pages >= 45  # NTAG213+ size
 
     def test_is_type2_tag(self):
-        from pm3py.sim.ndef import NfcType2Tag
+        from pm3py.transponders.hf.iso14443a.ndef import NfcType2Tag
         tag = xNT()
         assert isinstance(tag, NfcType2Tag)
 
@@ -77,7 +77,7 @@ class TestMagicMifareClassic:
 
 class TestFlexDF:
     def test_creates_desfire(self):
-        from pm3py.sim.desfire import DesfireTag
+        from pm3py.transponders.hf.iso14443a.nxp.desfire import DesfireTag
         tag = FlexDF()
         assert isinstance(tag, DesfireTag)
 
@@ -92,7 +92,7 @@ class TestNExT:
         # LF side is T5577 configured as EM4100
         assert lf.blocks[0] != 0
         # HF side is NfcType2Tag (xNT)
-        from pm3py.sim.ndef import NfcType2Tag
+        from pm3py.transponders.hf.iso14443a.ndef import NfcType2Tag
         assert isinstance(hf, NfcType2Tag)
 
     def test_both_sides_work(self):