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/manifest-route.test.ts

@@ -0,0 +1,82 @@
+/**
+ * Manifest route admin branding.
+ *
+ * The admin branding (logo, siteName, favicon) configured via the EmDash
+ * integration must be reflected in `/_emdash/api/manifest` so the React SPA
+ * can render the custom logo and site name. The route reads the branding
+ * from the per-request config on `locals.emdash.config.admin` (the same
+ * source `admin.astro` uses), not from a build-time global.
+ *
+ * Regression test for issue #835.
+ */
+
+import type { APIContext } from "astro";
+import { describe, expect, it } from "vitest";
+
+import { GET as getManifest } from "../../../src/astro/routes/api/manifest.js";
+
+interface ManifestEnvelope {
+	data: {
+		admin?: { logo?: string; siteName?: string; favicon?: string };
+		authMode: string;
+		signupEnabled?: boolean;
+		collections?: Record<string, unknown>;
+		plugins?: Record<string, unknown>;
+		taxonomies?: unknown[];
+		version?: string;
+	};
+}
+
+function makeContext(
+	adminBranding?: { logo?: string; siteName?: string; favicon?: string },
+	manifest?: unknown,
+): Parameters<typeof getManifest>[0] {
+	const locals = {
+		emdash: adminBranding
+			? {
+					// db is intentionally undefined so the signup-enabled query is skipped.
+					config: { admin: adminBranding },
+					getManifest: async () => manifest ?? null,
+				}
+			: undefined,
+	};
+
+	return { locals } as unknown as APIContext;
+}
+
+describe("manifest route admin branding", () => {
+	it("returns admin branding from locals.emdash.config.admin", async () => {
+		const branding = {
+			logo: "/logo.png",
+			siteName: "My Site",
+			favicon: "/favicon.ico",
+		};
+
+		const response = await getManifest(makeContext(branding));
+		expect(response.status).toBe(200);
+		const body = (await response.json()) as ManifestEnvelope;
+		expect(body.data.admin).toEqual(branding);
+	});
+
+	it("omits the admin field when no branding is configured", async () => {
+		const response = await getManifest(makeContext());
+		expect(response.status).toBe(200);
+		const body = (await response.json()) as ManifestEnvelope;
+		expect(body.data.admin).toBeUndefined();
+	});
+
+	it("returns admin branding even when getManifest() resolves to a built manifest", async () => {
+		const branding = { logo: "/brand.svg", siteName: "Brandname" };
+		const ctx = makeContext(branding, {
+			version: "test",
+			hash: "test",
+			collections: {},
+			plugins: {},
+			taxonomies: [],
+		});
+
+		const response = await getManifest(ctx);
+		const body = (await response.json()) as ManifestEnvelope;
+		expect(body.data.admin).toEqual(branding);
+	});
+});