Initial commit: simtrace2-pysniff v0.1.0

Python-based SIMtrace2 sniffer — drop-in replacement for simtrace2-sniff.
Single dependency (pyusb), auto-reconnect, GSMTAP/PCAP output, library API.

Modules:
  protocol.py — SIMtrace2 USB sniffing protocol parser
  device.py   — USB discovery + SniffSession with exponential backoff reconnect
  gsmtap.py   — GSMTAP UDP sender for Wireshark
  pcap.py     — PCAP file writer (LINKTYPE_GSMTAP)
  dump.py     — hex dump formatters + file output
  __main__.py — CLI entry point

Startup script sniff-start.sh handles udev permission checks and shows
install instructions. udev rule uses TAG+=uaccess (systemd-logind ACL).

pyproject.toml

@@ -0,0 +1,20 @@
+[build-system]
+requires = ["setuptools>=64"]
+build-backend = "setuptools.backends._legacy:_Backend"
+
+[project]
+name = "simtrace2-pysniff"
+version = "0.1.0"
+description = "Python-based sniffing tool for SIMtrace2 hardware (SIM card communication sniffer)"
+readme = {file = "README.md", content-type = "text/markdown"}
+license = {text = "GPL-2.0-or-later"}
+requires-python = ">=3.9"
+dependencies = [
+    "pyusb>=1.2",
+]
+
+[project.scripts]
+simtrace2-pysniff = "simtrace2_pysniff.__main__:main"
+
+[tool.setuptools.packages.find]
+include = ["simtrace2_pysniff*"]