feat(deepfield): 렌더 모드 판정(TDD) + useFieldMode 훅

lib/__tests__/deepfield-mode.test.ts

@@ -0,0 +1,26 @@
+import { describe, it, expect } from 'vitest';
+import { decideFieldMode } from '@/lib/deepfield-mode';
+
+const base = { reducedMotion: false, webglSupported: true, hardwareConcurrency: 8, viewportWidth: 1440 };
+
+describe('decideFieldMode', () => {
+  it('데스크톱 + WebGL = full', () => {
+    expect(decideFieldMode(base)).toBe('full');
+  });
+  it('reduced-motion이면 무조건 static', () => {
+    expect(decideFieldMode({ ...base, reducedMotion: true })).toBe('static');
+    expect(decideFieldMode({ ...base, reducedMotion: true, viewportWidth: 375 })).toBe('static');
+  });
+  it('WebGL 미지원이면 static', () => {
+    expect(decideFieldMode({ ...base, webglSupported: false })).toBe('static');
+  });
+  it('모바일 뷰포트(<768)는 lite', () => {
+    expect(decideFieldMode({ ...base, viewportWidth: 767 })).toBe('lite');
+  });
+  it('저성능 코어(<4)는 lite', () => {
+    expect(decideFieldMode({ ...base, hardwareConcurrency: 2 })).toBe('lite');
+  });
+  it('hardwareConcurrency 미보고(0/undefined)는 lite로 보수적 판정', () => {
+    expect(decideFieldMode({ ...base, hardwareConcurrency: 0 })).toBe('lite');
+  });
+});