Add system updates page to admin section

Add a new API endpoint and UI section for checking system updates, including internationalized locale strings and necessary dependency updates.

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lib/api-zod/src/generated/api.ts

@@ -14,6 +14,37 @@ export const HealthCheckResponse = zod.object({
   status: zod.string(),
 });
 
+/**
+ * Returns the local build version (read from version.json embedded at
+build time) and, if `LATEST_VERSION_URL` is configured on the
+server, the latest published version fetched from that URL. Admin
+only. Never performs an update — pure read.
+
+ * @summary Get current and latest system version
+ */
+export const GetSystemVersionResponse = zod.object({
+  current: zod.object({
+    version: zod.string(),
+    build: zod.string(),
+  }),
+  latest: zod.union([
+    zod.object({
+      version: zod.string(),
+      build: zod.string(),
+    }),
+    zod.null(),
+  ]),
+  status: zod.enum([
+    "up-to-date",
+    "update-available",
+    "not-configured",
+    "error",
+  ]),
+  errorMessage: zod.string().nullable(),
+  checkedAt: zod.coerce.date().nullable(),
+  configured: zod.boolean(),
+});
+
 /**
  * @summary Register a new user
  */