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/repository/profile_repo.go

@@ -34,6 +34,15 @@ func scanProfile(scan func(dest ...any) error) (*model.Profile, error) {
 	return p, nil
 }
 
+// CountActiveSelf returns non-deleted self profiles for the user.
+func (r *ProfileRepo) CountActiveSelf(ctx context.Context, userID uuid.UUID) (int, error) {
+	var n int
+	err := r.Pool.QueryRow(ctx, `
+		SELECT COUNT(*) FROM profiles
+		WHERE user_id=$1 AND relation='self' AND deleted_at IS NULL`, userID).Scan(&n)
+	return n, err
+}
+
 // Create inserts a profile.
 func (r *ProfileRepo) Create(ctx context.Context, userID uuid.UUID, relation, name string, birth time.Time, relationType *string, birthTime *string, birthPlace *string) (*model.Profile, error) {
 	row := r.Pool.QueryRow(ctx, `