refactor(cms): deduplicate shared admin components and fix studio batch completion

- fix(studio): stop markBatchDone infinite recursion so batches complete
- refactor(api): merge api-response into api and drop the duplicate module
- refactor(media): extract shared media loader and URL validator
- refactor(ui): extract shared LoadingSpinner for site and admin groups
- refactor(dates): consolidate raw date formatting into formatDate util
- refactor(logs): share a single generic log-list loader across tables
- refactor(theme): merge both ColorField components and reuse contrast helpers
- refactor(import): extract shared ImportErrorBanner and SearchInput
- chore(): remove dead theme-editor-tabs after inlining tab components

src/lib/api.test.ts

@@ -1,5 +1,22 @@
 import { describe, expect, it } from "vitest";
-import { apiUnavailable, pagination, positiveBigInt } from "@/lib/api";
+import { apiOk, apiUnavailable, pagination, positiveBigInt } from "@/lib/api";
+
+describe("apiOk", () => {
+	it("returns a BigInt-safe success envelope with ok: true", async () => {
+		const response = apiOk({ id: 9007199254740993n });
+
+		expect(response.status).toBe(200);
+		expect(response.headers.get("cache-control")).toBe("no-store");
+		await expect(response.json()).resolves.toEqual({
+			ok: true,
+			id: "9007199254740993",
+		});
+	});
+
+	it("allows empty payloads", async () => {
+		await expect(apiOk().json()).resolves.toEqual({ ok: true });
+	});
+});
 
 describe("apiUnavailable", () => {
 	it("returns a no-store 503 error without exposing internal details", async () => {