Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

packages/core/tests/unit/astro/routes.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { injectCoreRoutes } from "../../../src/astro/integration/routes.js";
+import { GET as getMediaFile } from "../../../src/astro/routes/api/media/file/[...key].js";
+
+function mockMediaContext(key: string | undefined) {
+	const download = vi.fn().mockResolvedValue({
+		body: new Uint8Array([1, 2, 3]),
+		contentType: "image/png",
+		size: 3,
+	});
+
+	return {
+		context: {
+			params: { key },
+			locals: {
+				emdash: {
+					storage: { download },
+				},
+			},
+		} as Parameters<typeof getMediaFile>[0],
+		download,
+	};
+}
+
+describe("core media route injection", () => {
+	it("uses a catch-all media file route so storage keys can contain slashes", () => {
+		const routes: Array<{ pattern: string; entrypoint: string }> = [];
+		injectCoreRoutes((route) => {
+			routes.push({
+				...route,
+				entrypoint: route.entrypoint.replaceAll("\\", "/"),
+			});
+		});
+
+		expect(routes).toContainEqual(
+			expect.objectContaining({
+				pattern: "/_emdash/api/media/file/[...key]",
+				entrypoint: expect.stringContaining("api/media/file/[...key].ts"),
+			}),
+		);
+	});
+});
+
+describe("media file catch-all route", () => {
+	it("passes slash-containing keys through to storage.download", async () => {
+		const { context, download } = mockMediaContext("nested/path/file.png");
+
+		const response = await getMediaFile(context);
+		expect(response.status).toBe(200);
+		expect(download).toHaveBeenCalledWith("nested/path/file.png");
+	});
+
+	it("returns not found when the catch-all key is missing", async () => {
+		const { context, download } = mockMediaContext(undefined);
+
+		const response = await getMediaFile(context);
+		expect(response.status).toBe(404);
+		expect(download).not.toHaveBeenCalled();
+	});
+});