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

templates/marketing-cloudflare/.mcp.json

@@ -0,0 +1,8 @@
+{
+	"mcpServers": {
+		"emdash-docs": {
+			"type": "http",
+			"url": "https://docs.emdashcms.com/mcp"
+		}
+	}
+}