Add a real cover for singles

e2e/navegacion.e2e.ts

@@ -116,6 +116,18 @@ test.describe('Navegación', () => {
 		await expect(page.getByText('Ese tema no existe.')).toBeVisible();
 		await expect(page).toHaveTitle(/Página no encontrada/);
 	});
+
+	test('los singles sin cubierta propia usan una portada válida', async ({ page }) => {
+		const respuesta = page.waitForResponse((r) => r.url().endsWith('/images/singles/portada.svg'));
+
+		await page.goto('/canciones/dorina');
+
+		await expect(page.getByRole('img', { name: 'Portada de Dorina' })).toHaveAttribute(
+			'src',
+			'/images/singles/portada.svg'
+		);
+		expect((await respuesta).status()).toBe(200);
+	});
 });
 
 test.describe('La página de error', () => {

static/images/singles/portada.svg

@@ -0,0 +1,33 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 1200" role="img" aria-labelledby="titulo descripcion">
+	<title id="titulo">Singles de Senza Paura</title>
+	<desc id="descripcion">Cubierta azul noche con líneas doradas y el título Singles.</desc>
+	<defs>
+		<radialGradient id="fondo" cx="48%" cy="38%" r="76%">
+			<stop offset="0" stop-color="#123b61" />
+			<stop offset="0.56" stop-color="#001b35" />
+			<stop offset="1" stop-color="#000719" />
+		</radialGradient>
+		<linearGradient id="oro" x1="0" y1="0" x2="1" y2="1">
+			<stop offset="0" stop-color="#f3d79b" />
+			<stop offset="0.5" stop-color="#e2b567" />
+			<stop offset="1" stop-color="#9c6d29" />
+		</linearGradient>
+	</defs>
+
+	<rect width="1200" height="1200" fill="url(#fondo)" />
+	<rect x="58" y="58" width="1084" height="1084" fill="none" stroke="#e2b567" stroke-opacity="0.34" stroke-width="2" />
+	<circle cx="600" cy="508" r="292" fill="none" stroke="#eef1f7" stroke-opacity="0.08" stroke-width="86" />
+	<circle cx="600" cy="508" r="182" fill="none" stroke="#e2b567" stroke-opacity="0.22" stroke-width="2" />
+	<circle cx="600" cy="508" r="20" fill="url(#oro)" />
+
+	<g fill="none" stroke="url(#oro)" stroke-linecap="round" stroke-width="8">
+		<path d="M248 508h52l22-54 36 114 42-192 50 264 48-222 48 180 42-90h404" opacity="0.86" />
+		<path d="M248 552h704" opacity="0.18" stroke-width="2" />
+	</g>
+
+	<text x="600" y="178" text-anchor="middle" fill="#eef1f7" font-family="Georgia, 'Times New Roman', serif" font-size="52" letter-spacing="16">SENZA PAURA</text>
+	<line x1="464" y1="212" x2="736" y2="212" stroke="#e2b567" stroke-width="2" />
+
+	<text x="600" y="930" text-anchor="middle" fill="#eef1f7" font-family="Georgia, 'Times New Roman', serif" font-size="124" letter-spacing="10">SINGLES</text>
+	<text x="600" y="1002" text-anchor="middle" fill="#c2cbdb" font-family="system-ui, sans-serif" font-size="24" letter-spacing="12">CANCIONES FUERA DE ÁLBUM</text>
+</svg>