feat(inventory): show NVMe PCIe link gen/width, flag downtrains — 0.38.0

Each NVMe drive's Inventory entry now shows its negotiated PCIe link (e.g.
'· PCIe Gen4 x4') from sysfs (current/max link speed+width), and flags drives
running below their capability ('Gen3 x4 (capable of Gen4 x4)') — so you can
confirm a Gen4 SSD is in a Gen4 slot. SATA disks show no PCIe link. Renders in
the GUI Inventory, CLI, and the Markdown/JSON export automatically. +tests.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "rigdoctor"
-version = "0.37.1"
+version = "0.38.0"
 description = "Modular hardware monitoring & crash diagnostics for Linux gamers."
 readme = "README.md"
 requires-python = ">=3.11"