feat(v2): add annotated evidence and alert dispatch

v2/internal/render/overlay_test.go

@@ -0,0 +1,37 @@
+package render
+
+import (
+	"image/color"
+	"testing"
+	"time"
+
+	"silverpose/v2/internal/fall"
+)
+
+func TestRenderUsesCriticalBorderOnlyForConfirmed(t *testing.T) {
+	bgr := make([]byte, 4*3*3)
+	for index := range bgr {
+		bgr[index] = 64
+	}
+	normal, err := Render(bgr, 4, 3, fall.FrameResult{}, time.Date(2026, 7, 22, 8, 0, 0, 0, time.UTC))
+	if err != nil {
+		t.Fatal(err)
+	}
+	confirmed, err := Render(bgr, 4, 3, fall.FrameResult{People: []fall.PersonAnalysis{{State: fall.Confirmed}}}, time.Date(2026, 7, 22, 8, 0, 0, 0, time.UTC))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := normal.RGBAAt(0, 0); got != (color.RGBA{R: 64, G: 64, B: 64, A: 255}) {
+		t.Fatalf("normal border = %#v", got)
+	}
+	if got := confirmed.RGBAAt(0, 0); got != criticalColor {
+		t.Fatalf("confirmed border = %#v, want %#v", got, criticalColor)
+	}
+}
+
+func TestRenderRejectsInvalidBGRLength(t *testing.T) {
+	_, err := Render([]byte{1, 2, 3}, 2, 2, fall.FrameResult{}, time.Time{})
+	if err == nil {
+		t.Fatal("expected invalid frame length error")
+	}
+}