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/admin/tests/lib/api-client.test.ts

@@ -0,0 +1,71 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+
+import { apiFetch, fetchManifest } from "../../src/lib/api/client";
+
+describe("apiFetch", () => {
+	let fetchSpy: ReturnType<typeof vi.fn>;
+	const originalFetch = globalThis.fetch;
+
+	beforeEach(() => {
+		fetchSpy = vi.fn().mockResolvedValue(new Response(JSON.stringify({}), { status: 200 }));
+		globalThis.fetch = fetchSpy;
+	});
+
+	afterEach(() => {
+		globalThis.fetch = originalFetch;
+	});
+
+	it("adds X-EmDash-Request header", async () => {
+		await apiFetch("/test");
+		expect(fetchSpy).toHaveBeenCalledOnce();
+		const [, init] = fetchSpy.mock.calls[0]!;
+		const headers = new Headers(init.headers);
+		expect(headers.get("X-EmDash-Request")).toBe("1");
+	});
+
+	it("preserves existing headers", async () => {
+		await apiFetch("/test", { headers: { "Content-Type": "application/json" } });
+		const [, init] = fetchSpy.mock.calls[0]!;
+		const headers = new Headers(init.headers);
+		expect(headers.get("Content-Type")).toBe("application/json");
+		expect(headers.get("X-EmDash-Request")).toBe("1");
+	});
+
+	it("passes through other init options", async () => {
+		await apiFetch("/test", { method: "POST", body: "data" });
+		const [, init] = fetchSpy.mock.calls[0]!;
+		expect(init.method).toBe("POST");
+		expect(init.body).toBe("data");
+	});
+});
+
+describe("fetchManifest", () => {
+	const originalFetch = globalThis.fetch;
+
+	afterEach(() => {
+		globalThis.fetch = originalFetch;
+	});
+
+	it("returns parsed manifest on success", async () => {
+		const manifest = {
+			version: "1.0",
+			collections: {},
+			plugins: {},
+			authMode: "passkey",
+			hash: "abc",
+		};
+		globalThis.fetch = vi
+			.fn()
+			.mockResolvedValue(new Response(JSON.stringify({ data: manifest }), { status: 200 }));
+		const result = await fetchManifest();
+		expect(result.version).toBe("1.0");
+		expect(result.authMode).toBe("passkey");
+	});
+
+	it("throws on non-ok response", async () => {
+		globalThis.fetch = vi
+			.fn()
+			.mockResolvedValue(new Response("", { status: 500, statusText: "Internal Server Error" }));
+		await expect(fetchManifest()).rejects.toThrow("Failed to fetch manifest");
+	});
+});