cimery Sprint 2 — PSC-I 기하학 + viewer 개편 + OCCT optional

kernel:
- PureRustKernel: PSC-I 단면 14-vertex polygon 스위프, flat normals
  56 triangles / 168 vertices, 법선 단위벡터 검증 포함
- opencascade 의존성 optional feature (--features occt)로 격리
  → OCCT 없이도 전체 빌드 가능
- psc_i.rs: 프로파일 검증, AABB, 법선 테스트 6개

viewer:
- camera.rs: arcball orbit (middle-mouse drag + scroll zoom)
- shader.wgsl: MVP matrix uniform + 방향성 조명 (콘크리트 베이지)
- lib.rs: depth buffer, index 렌더, 실제 Mesh 업로드
  StubKernel → PureRustKernel → OcctKernel 교체 경로 문서화

CLAUDE.md: MVP 품질 원칙 강화 ("아키텍처 임의 변경 절대 불가")

cargo test --workspace (viewer 제외) 43개 전부 통과

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cimery/.cargo/config.toml

@@ -0,0 +1,5 @@
+# Provide MSVC standard library paths for opencascade-sys CXX compilation.
+# Forward slashes work with cl.exe.
+[env]
+INCLUDE = { value = "C:/Program Files/Microsoft Visual Studio/2022/Professional/VC/Tools/MSVC/14.44.35207/include;C:/Program Files (x86)/Windows Kits/10/Include/10.0.26100.0/ucrt;C:/Program Files (x86)/Windows Kits/10/Include/10.0.26100.0/um;C:/Program Files (x86)/Windows Kits/10/Include/10.0.26100.0/shared", force = true }
+LIB    = { value = "C:/Program Files/Microsoft Visual Studio/2022/Professional/VC/Tools/MSVC/14.44.35207/lib/x64;C:/Program Files (x86)/Windows Kits/10/Lib/10.0.26100.0/ucrt/x64;C:/Program Files (x86)/Windows Kits/10/Lib/10.0.26100.0/um/x64", force = true }