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.

README.md

@@ -662,7 +662,7 @@ The bundled Python server wraps [pySim](https://osmocom.org/projects/pysim/wiki)
 | `setup.sh` / `setup.bat` | Creates `.venv/`, installs pysim and the server. Run once after cloning. |
 | `start.sh` / `start.bat` | Starts the server from the venv (serves the PWA + API on `:8080`). |
 
-`start.sh` auto-detects the reader (PC/SC if `pcscd` is running, else `/dev/ttyUSB0`); `start.bat` always uses `-p 0` (PC/SC is built into Windows). If no reader is found the server still starts ("Reader: none") — initialize the card later via the **Equip** button.
+`start.sh` auto-detects the reader (PC/SC if `pcscd` is running, else `/dev/ttyUSB0`); `start.bat` always uses `-p 0` (PC/SC is built into Windows). Extra arguments are passed through to the server, e.g. `./start.sh --gsmtap` or `start.bat --gsmtap 10.0.0.5:4729`. If no reader is found the server still starts ("Reader: none") — initialize the card later via the **Equip** button.
 
 ### Manual installation
 
@@ -685,6 +685,7 @@ pysim-simple-server --http-port 8080
 | `-d` / `--device` | Serial device path |
 | `--no-card-init` | Skip card init to preserve the CAT session (no file manager) |
 | `--apdu-trace` | Log APDU-level traces to stderr |
+| `--gsmtap [HOST[:PORT]]` | Stream every APDU (and the card ATR at equip) as GSMTAP-SIM UDP packets for Wireshark / SIMtrace Analyser (`--capture gsmtap`); default target `127.0.0.1:4729`. Combines with `--apdu-trace` |
 | `--log-requests` | Log request/response payloads to stderr |
 | `--sms-oa` / `--sms-sm-sc` | SMS-DELIVER originating address / SM-SC for PoR-in-submit |
 | `--terminal-profile` | TERMINAL PROFILE payload hex (default: 33-byte real-handset profile that advertises BIP events/commands; the live card ignores HTTP OTA without it) |