feat(ECR-011): 昵称、首页贴士与档案 Self 唯一/合盘交叉校验

每账号仅一条 self（migration 40902）；合盘只选 TA；账号昵称可改；首页穿衣/颜色/养生贴士。

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/internal/yijing/seed_test.go

@@ -0,0 +1,29 @@
+package yijing
+
+import (
+	"testing"
+	"time"
+)
+
+func TestSeedStableSameInputs(t *testing.T) {
+	bt := "10:30"
+	now := time.Date(2026, 8, 11, 19, 0, 0, 0, time.FixedZone("CST", 8*3600))
+	a := Seed("1990-05-12", &bt, now)
+	b := Seed("1990-05-12", &bt, now)
+	if a.GuaIndex != b.GuaIndex || a.GuaName != b.GuaName || a.Line != b.Line {
+		t.Fatalf("expected stable seed, got %+v vs %+v", a, b)
+	}
+	if a.GuaIndex < 1 || a.GuaIndex > 64 {
+		t.Fatalf("gua out of range: %d", a.GuaIndex)
+	}
+}
+
+func TestSeedChangesWithHour(t *testing.T) {
+	now1 := time.Date(2026, 8, 11, 9, 0, 0, 0, time.FixedZone("CST", 8*3600))
+	now2 := time.Date(2026, 8, 11, 18, 0, 0, 0, time.FixedZone("CST", 8*3600))
+	a := Seed("1990-05-12", nil, now1)
+	b := Seed("1990-05-12", nil, now2)
+	if a.DayPart == b.DayPart {
+		t.Fatalf("expected different day parts, both %s", a.DayPart)
+	}
+}