fix: harden webui path and account pool compatibility

internal/admin/handler_test.go

@@ -0,0 +1,28 @@
+package admin
+
+import "testing"
+
+func TestToAccountMissingFieldsRemainEmpty(t *testing.T) {
+	acc := toAccount(map[string]any{
+		"email":    "user@example.com",
+		"password": "secret",
+	})
+	if acc.Email != "user@example.com" {
+		t.Fatalf("unexpected email: %q", acc.Email)
+	}
+	if acc.Mobile != "" {
+		t.Fatalf("expected empty mobile, got %q", acc.Mobile)
+	}
+	if acc.Token != "" {
+		t.Fatalf("expected empty token, got %q", acc.Token)
+	}
+}
+
+func TestFieldStringNilToEmpty(t *testing.T) {
+	if got := fieldString(map[string]any{"token": nil}, "token"); got != "" {
+		t.Fatalf("expected empty string for nil field, got %q", got)
+	}
+	if got := fieldString(map[string]any{}, "token"); got != "" {
+		t.Fatalf("expected empty string for missing field, got %q", got)
+	}
+}