feat(v2): add fall event regression engine

v2/internal/pose/preprocess_test.go

@@ -0,0 +1,39 @@
+package pose
+
+import "testing"
+
+func TestPreprocessBGRUsesUltralyticsPaddingAndRGBCHW(t *testing.T) {
+	// A 2x1 BGR frame letterboxes into a 4x4 tensor with one row of 114-gray
+	// padding above and below. The rightmost source pixel is pure blue in BGR.
+	frame := []byte{0, 0, 0, 255, 0, 0}
+
+	input, transform, err := PreprocessBGR(frame, 2, 1, 4)
+	if err != nil {
+		t.Fatalf("PreprocessBGR returned an error: %v", err)
+	}
+	if transform.ResizedWidth != 4 || transform.ResizedHeight != 2 || transform.PadTop != 1 {
+		t.Fatalf("unexpected transform: %+v", transform)
+	}
+
+	const plane = 16
+	padding := float32(114.0 / 255.0)
+	if got := input[2*plane+0]; got != padding {
+		t.Fatalf("top padding blue = %v, want %v", got, padding)
+	}
+	if got := input[0*plane+1*4+3]; got != 0 {
+		t.Fatalf("red channel = %v, want 0", got)
+	}
+	if got := input[1*plane+1*4+3]; got != 0 {
+		t.Fatalf("green channel = %v, want 0", got)
+	}
+	if got := input[2*plane+1*4+3]; got != 1 {
+		t.Fatalf("blue channel = %v, want 1", got)
+	}
+}
+
+func TestPreprocessBGRRejectsTruncatedFrame(t *testing.T) {
+	_, _, err := PreprocessBGR([]byte{0}, 2, 1, 4)
+	if err == nil {
+		t.Fatal("PreprocessBGR accepted a truncated BGR frame")
+	}
+}