Replace progpib.py stub with a proper installable package

Builds a modern, testable API for the Prologix GPIB-ETHERNET controller
(GPIB-USB structurally supported but untested, no hardware available):
Transport abstraction (Ethernet now, serial later), GpibController for
the full "++" command set, a clean-room netfinder discovery client that
fixes a real chr()/struct-format bug present in vendortools/nfutil.py,
and a CLI (discover/config/info/terminal). vendortools/, pty-gpib-emulator/,
sampledata.txt and the manual PDF are kept untouched as reference material.

Depends on the sibling bits package (editable, not yet pinned -- see its
own commit) for MAC formatting and IEEE-488.2 status-byte bit access.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,24 @@
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[project]
+name = "progpib"
+version = "0.1.0"
+description = "Modern Python 3 API for Prologix GPIB-ETHERNET (and, structurally but unvalidated, GPIB-USB) controllers"
+readme = "README.md"
+requires-python = ">=3.10"
+license = { text = "MIT" }
+dependencies = [
+    "pyserial>=3.5",
+    "binary-bits",
+]
+
+[project.optional-dependencies]
+dev = ["pytest>=7"]
+
+[project.scripts]
+progpib = "progpib.cli:main"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]