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/components/ThemeToggle.test.tsx

@@ -0,0 +1,69 @@
+import * as React from "react";
+import { describe, it, expect, beforeEach } from "vitest";
+
+import { ThemeProvider } from "../../src/components/ThemeProvider";
+import { ThemeToggle } from "../../src/components/ThemeToggle";
+import { render } from "../utils/render.tsx";
+
+function TestThemeToggle({ defaultTheme = "system" as "system" | "light" | "dark" }) {
+	return (
+		<ThemeProvider defaultTheme={defaultTheme}>
+			<ThemeToggle />
+		</ThemeProvider>
+	);
+}
+
+describe("ThemeToggle", () => {
+	beforeEach(() => {
+		localStorage.clear();
+		document.documentElement.removeAttribute("data-theme");
+	});
+
+	it("renders with system theme by default", async () => {
+		const screen = await render(<TestThemeToggle />);
+		const button = screen.getByRole("button");
+		await expect.element(button).toBeInTheDocument();
+		// System theme shows Monitor icon - check the title
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("System"));
+	});
+
+	it("cycles from system to light on click", async () => {
+		const screen = await render(<TestThemeToggle />);
+		const button = screen.getByRole("button");
+		await button.click();
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("Light"));
+	});
+
+	it("cycles through system -> light -> dark -> system", async () => {
+		const screen = await render(<TestThemeToggle />);
+		const button = screen.getByRole("button");
+
+		// Start: system
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("System"));
+
+		// Click 1: light
+		await button.click();
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("Light"));
+
+		// Click 2: dark
+		await button.click();
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("Dark"));
+
+		// Click 3: back to system
+		await button.click();
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("System"));
+	});
+
+	it("persists theme to localStorage", async () => {
+		const screen = await render(<TestThemeToggle />);
+		const button = screen.getByRole("button");
+		await button.click(); // system -> light
+		expect(localStorage.getItem("emdash-theme")).toBe("light");
+	});
+
+	it("starts with light theme when defaultTheme is light", async () => {
+		const screen = await render(<TestThemeToggle defaultTheme="light" />);
+		const button = screen.getByRole("button");
+		await expect.element(button).toHaveAttribute("title", expect.stringContaining("Light"));
+	});
+});