fix(stl-game-config): detect primary-display HDR and the gaming GPU correctly

[St0nefish]

Summary

Fixes two detection bugs in stl-game-config's system-info.sh.

HDR (#182). check_kde_hdr_enabled always returned false: kscreen-doctor -o
colorizes through a pipe, so HDR: enabled never matched literally, and
head -1 read whichever output was listed first rather than the primary. It now
parses kscreen-doctor -j with jq and reports hdr of the enabled output with
priority == 1.

GPU vendor. detect_gpu_vendor's sysfs checks never matched (ls of the
vendor file instead of cat) and only looked at card0, which is often the
CPU's iGPU (e.g. Ryzen iGPU as card0, RTX 5090 as card1). It now ranks every
/sys/class/drm/cardN: NVIDIA > discrete AMD > Intel > AMD iGPU (amdgpu with
VRAM < 2 GiB), falling back to nvidia-smi -L (proprietary driver without
nvidia-drm) and then vulkaninfo.

Review fixes: the Vulkan fallback grep is now -q (matched lines leaked into
the JSON output), and the nvidia-smi fallback was restored after review.

Note: the format-on-save hook reindented system-info.sh from 4 to 2 spaces —
review it with whitespace hidden (git diff -w).

• stl-game-config 1.2.1 → 1.2.2 (Claude + Copilot manifests)

Test plan

• New tests/stl-game-config/test-system-info.sh — 14 cases (7 HDR fixtures via
  a mocked kscreen-doctor -j, 7 GPU fixtures via STL_DRM_ROOT), all passing
• bash .github/scripts/validate-all.sh — all checks pass
• Live run on KDE Wayland, AMD iGPU + RTX 5090, HDR on primary:
  {"gpu_vendor":"nvidia","compositor":"kde","kde_hdr_enabled":true}

Fixes #182

🤖 Generated with Claude Code