feat(api, agents, i18n): enhance settlement features and multi-language support

Added new types and API functions for settlement period summaries and credit ledgers, improving the management of agent settlements. Updated the admin console to reflect these changes, enhancing user experience with better navigation and data presentation. Additionally, expanded multi-language support by incorporating new translations in English, Nepali, and Chinese for settlement-related terms, ensuring consistency across the platform.

src/lib/admin-site-display.ts

@@ -0,0 +1,13 @@
+/** 后台展示用站点名：优先中文名，不暴露内部 code。 */
+export function formatAdminSiteLabel(
+  name?: string | null,
+  code?: string | null,
+): string {
+  const trimmedName = name?.trim();
+  if (trimmedName) {
+    return trimmedName;
+  }
+
+  const trimmedCode = code?.trim();
+  return trimmedCode ?? "—";
+}