feat: Initial release v0.1.0

STP/STEP 3D viewer (WPF, .NET 8) - CADability + HelixToolkit.Wpf:

- Multi-file import (STEP/STL/DXF) with STEP assembly tree
  (per-node visibility/color cascade, zoom-to)
- Measurements: point / distance / edge / face / circle / angle /
  face-to-face distance (B-rep exact where available)
- Assembly verification: two-point align (translate), 3-point align
  (rotate+translate via RigidAlign), axis rotate 90, interference
  check (tri-tri intersection + min gap)
- Section view (CPU mesh clipping, originals preserved)
- mm/inch toggle, CSV export (UTF-8 BOM), 2x PNG screenshot
- Performance: per-file merged edge lines, per-leaf merged mesh in
  browse mode, no BackMaterial on closed solids, edge suspend during
  camera interaction, parallel leaf triangulation with retry
- SmokeTest CLI: import pipeline, --tree, --clip-test,
  --interference-test, --align-test (all passing)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

secret/run-STPViewer.sh.example

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+# ══════════════════════════════════════════════════════════════════
+#  run-STPViewer.sh 範本（Git Bash on Windows）
+#
+#  第一次 clone 下來：
+#    cd secret
+#    cp run-STPViewer.sh.example run-STPViewer.sh
+#    chmod +x run-STPViewer.sh
+#    ./run-STPViewer.sh
+#
+#  secret/ 下除 README.md 和 .example 外皆已 gitignore。
+# ══════════════════════════════════════════════════════════════════
+
+set -euo pipefail
+
+# ─── secret（本專案目前無 DB / ApiKey；未來需要時在此 export） ────
+# export SomeService__ApiKey="__CHANGE_ME__"
+
+# ══════════════════════════════════════════════════════════════════
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
+
+cd "${REPO_ROOT}"
+exec dotnet run --project src/STPViewer