Alternative.images: array of urls, rendered as a Swiper card deck

image: Option<String> becomes images: Vec<String> (nothing in live
content used the old field). One url renders as the plain banner it
was; several become a swipeable cards-effect deck via Swiper Element
12.2.0, vendored into public/ (MIT) like prosekit-editor.js/yes.js
rather than pulled from a CDN - the bundle only loads on pages where
some alternative actually declares more than one image.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/content.rs

@@ -60,13 +60,15 @@ pub struct Alternative {
     pub consequence: Vec<String>,
     #[serde(default)]
     pub encouragements: Vec<String>,
-    /// A banner image url, rendered above the description - purely
-    /// decorative, no upload/hosting mechanism of its own, just an
-    /// already-hosted url the browser fetches directly (unlike
-    /// `ResourceSource::Url`, this is never fetched server-side, so it
-    /// carries none of that variant's SSRF concern).
+    /// Banner image urls, rendered above the description - one renders
+    /// as a plain image, several as a swipeable card deck (Swiper
+    /// Element, vendored in `public/`). Purely decorative, no
+    /// upload/hosting mechanism of their own, just already-hosted urls
+    /// the browser fetches directly (unlike `ResourceSource::Url`,
+    /// never fetched server-side, so none of that variant's SSRF
+    /// concern).
     #[serde(default)]
-    pub image: Option<String>,
+    pub images: Vec<String>,
     #[serde(default)]
     pub features: Vec<Feature>,
     /// Names a NATS KV bucket to also durably store this submission