test: add unit tests for pure logic modules

Add 22 test files covering imager, soundtracks, browser-headers, source-keys (figure/pet/effect), effect-source, plus catalog-translations, catalog-layouts, client-translation-files, translations-utils, and various admin/services/helpers modules. Total test count increases by 120+.

src/lib/admin/notice.test.ts

@@ -1,24 +1,26 @@
 import { describe, expect, it } from "vitest";
-import { adminMutationNotice } from "@/lib/admin/notice";
+import { adminMutationNotice } from "./notice";
 
 describe("adminMutationNotice", () => {
-	it("maps a successful redirect to a safe notice", () => {
+	it("returns a danger notice when there is an error", () => {
+		expect(adminMutationNotice({ error: "boom" })).toEqual({
+			tone: "danger",
+			label: "Error",
+			message: "The operation could not be completed.",
+		});
+	});
+	it("returns a success notice when saved is 1", () => {
 		expect(adminMutationNotice({ saved: "1" })).toEqual({
 			tone: "ok",
 			label: "Saved",
 			message: "Changes were saved successfully.",
 		});
 	});
-
-	it("maps an error code without reflecting arbitrary query text", () => {
-		expect(adminMutationNotice({ error: "<script>" })).toEqual({
-			tone: "danger",
-			label: "Error",
-			message: "The operation could not be completed.",
-		});
-	});
-
-	it("returns null when there is no mutation result", () => {
+	it("returns null when nothing is set", () => {
 		expect(adminMutationNotice({})).toBeNull();
 	});
+	it("prioritises errors over saved flags", () => {
+		const notice = adminMutationNotice({ saved: "1", error: "x" });
+		expect(notice?.tone).toBe("danger");
+	});
 });