feat: GSMTAP-SIM APDU streaming for Wireshark / SIMtrace Analyser (v3.1.0)

Streams every APDU the server sends or receives as GSMTAP-SIM UDP packets,
so a live capture can be followed in Wireshark or the SIMtrace Analyser
without a hardware sniffer.  CLI-only: --gsmtap [HOST[:PORT]], default
target 127.0.0.1:4729; no UI or API.

- pysim_simple_server/gsmtap.py: 16-byte big-endian GSMTAP-SIM header
  (type 0x04, sub_type 0x00 = APDU / 0x01 = ATR) + raw APDU bytes, a
  fire-and-forget non-blocking sender that never raises into card I/O, an
  ApduTracer (a response is sent as data + SW1SW2, the wire form) and a
  fan-out tracer.  The packet layout is byte-identical to
  sigrok-iso7816-stream / simtrace2-sniff (verified against the sigrok
  module) and is what the analyser's GSMTAP receiver expects.
- __main__.py: --gsmtap option, tracer installed on the shared transport
  before the first APDU, combined with --apdu-trace via the fan-out and
  re-attached across equips (pySim nulls the tracer on every equip); one
  ATR packet per equip from _apply_equipped_card/_send_gsmtap_atr.
- start.sh/start.bat: forward their extra arguments to the server, so
  ./start.sh --gsmtap works.
- tests: packet layout, loopback UDP delivery, tracer mapping, target
  parsing, fan-out; docs (READMEs, help EN/RU, AGENTS); version 3.1.0,
  sw.js simple-v235.

pysim_simple_server/server.py

@@ -28,7 +28,7 @@ from osmocom.tlv import BER_TLV_IE
 from osmocom.utils import rpad
 
 
-VERSION = '3.0.1'
+VERSION = '3.1.0'
 
 MAX_ENVELOPE_SEGMENTS = 5  # max SMS segments for outgoing C-APDU in ENVELOPE
 
@@ -2532,10 +2532,34 @@ def _handle_card_disconnect():
     _reset_proactive_log()
 
 
+def _send_gsmtap_atr(server):
+    """Stream the card's ATR as a GSMTAP-SIM packet (--gsmtap only).
+
+    Sent at every equip so a GSMTAP receiver (SIMtrace Analyser, Wireshark)
+    has the session context before the first APDU of the new session."""
+    sender = getattr(server, 'gsmtap', None)
+    if sender is None:
+        return
+    rs = getattr(server, 'rs', None)
+    atr = None
+    if rs is not None:
+        try:
+            atr = (rs.identity or {}).get('ATR')
+        except Exception:
+            atr = None
+    if not atr:
+        return
+    try:
+        sender.send_atr(bytes.fromhex(atr))
+    except (ValueError, TypeError):
+        pass
+
+
 def _apply_equipped_card(server):
     """Common post-equip state refresh + TERMINAL PROFILE, shared by the
     /api/command equip branch and the auto-equip worker."""
     global _CARD_CONNECTED
+    _send_gsmtap_atr(server)
     server.stk_pending = None
     server.menu_active = False
     _cancel_menu_timeout()