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/photo-files.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from "vitest";
+import { tryRemoveLocalPhotoFile } from "./photo-files";
+
+describe("tryRemoveLocalPhotoFile", () => {
+	it("returns false for empty or nullish urls", async () => {
+		expect(await tryRemoveLocalPhotoFile("")).toBe(false);
+		expect(await tryRemoveLocalPhotoFile("   ")).toBe(false);
+	});
+
+	it("returns false for external urls not on this app origin", async () => {
+		expect(
+			await tryRemoveLocalPhotoFile("https://evil.example.com/photos/x.png"),
+		).toBe(false);
+	});
+
+	it("returns false for urls without a leading slash", async () => {
+		expect(await tryRemoveLocalPhotoFile("photos/x.png")).toBe(false);
+	});
+
+	it("blocks path traversal", async () => {
+		expect(await tryRemoveLocalPhotoFile("/../../etc/passwd")).toBe(false);
+		expect(await tryRemoveLocalPhotoFile("/photos/..%2f..%2fetc/passwd")).toBe(
+			false,
+		);
+	});
+
+	it("returns false when the target file does not exist", async () => {
+		expect(
+			await tryRemoveLocalPhotoFile("/photos/definitely-missing.png"),
+		).toBe(false);
+	});
+});