feat: add image URL fetching service with tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/services/image.service.test.ts

@@ -0,0 +1,45 @@
+import { afterEach, describe, expect, it } from "bun:test";
+import { existsSync, rmSync } from "node:fs";
+import { fetchImageFromUrl } from "../../src/server/services/image.service.ts";
+
+const TEST_UPLOADS_DIR = "test-uploads";
+
+describe("Image Service", () => {
+	afterEach(() => {
+		if (existsSync(TEST_UPLOADS_DIR)) {
+			rmSync(TEST_UPLOADS_DIR, { recursive: true });
+		}
+	});
+
+	describe("fetchImageFromUrl", () => {
+		it("fetches a valid image URL and saves to disk", async () => {
+			const imageUrl =
+				"https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png";
+			const result = await fetchImageFromUrl(imageUrl, TEST_UPLOADS_DIR);
+
+			expect(result.filename).toMatch(/^\d+-[\w-]+\.png$/);
+			expect(result.sourceUrl).toBe(imageUrl);
+
+			const filePath = `${TEST_UPLOADS_DIR}/${result.filename}`;
+			expect(existsSync(filePath)).toBe(true);
+		});
+
+		it("rejects non-image content type", async () => {
+			await expect(
+				fetchImageFromUrl("https://example.com/", TEST_UPLOADS_DIR),
+			).rejects.toThrow("Invalid content type");
+		});
+
+		it("rejects invalid URL format", async () => {
+			await expect(
+				fetchImageFromUrl("not-a-url", TEST_UPLOADS_DIR),
+			).rejects.toThrow("Invalid URL format");
+		});
+
+		it("rejects non-HTTP protocols", async () => {
+			await expect(
+				fetchImageFromUrl("ftp://example.com/image.png", TEST_UPLOADS_DIR),
+			).rejects.toThrow("URL must use HTTP or HTTPS");
+		});
+	});
+});