Fix sharp in container, add admin downloads and anchor mark

- ship libvips with the runtime image so POST /api/v1/media stops failing
- admin downloads openapi.json and the style guide via session, no token
- copy rows for both API addresses
- anchor mark in the wordmark and a favicon

src/app/admin/api/files/style-guide/route.ts

@@ -0,0 +1,14 @@
+import { readStyleGuide, styleGuideResponse } from '~/lib/api-docs'
+import { requireAdminArea } from '~/lib/auth-guards'
+
+export async function GET() {
+	await requireAdminArea()
+
+	const text = await readStyleGuide()
+
+	if (text === null) {
+		return new Response('docs/style-guide.md fehlt.', { status: 500 })
+	}
+
+	return styleGuideResponse(text, true)
+}