fix(rusty-image): preserve animated GIFs through markdown image processing

RustyCMS /api/transform decodes only the first frame of animated formats,
which silently kills GIF animation when markdown HTML images get rewritten
to /api/transform URLs. Skip the transform for `.gif` URLs so the original
asset URL flows through and animation survives.

Also picks up an arrow-right entry in the iconify mdi subset generated
during a UI build.

src/lib/rusty-image.ts

@@ -153,6 +153,10 @@ const MARKDOWN_IMAGE_PARAMS: RustyImageTransformParams = {
 
 const IMG_SRC_REGEX = /<img\s+([^>]*?)src\s*=\s*["']([^"']+)["']([^>]*)>/gi;
 
+// Animated formats — skip transform, keep original URL so animation survives.
+// RustyCMS /api/transform decodes only the first frame.
+const ANIMATED_EXT_REGEX = /\.gif(\?|$)/i;
+
 export async function processMarkdownHtmlImages(html: string, _baseUrl?: string, transformParams: RustyImageTransformParams = MARKDOWN_IMAGE_PARAMS): Promise<string> {
   const matches = [...html.matchAll(IMG_SRC_REGEX)];
   const replacements: { index: number; length: number; newBlock: string }[] = [];
@@ -160,7 +164,8 @@ export async function processMarkdownHtmlImages(html: string, _baseUrl?: string,
     const rawSrc = m[2];
     const url = rawSrc.startsWith('//') ? `https:${rawSrc}` : rawSrc;
     if (!url.startsWith('http')) continue;
-    const transformedPath = getCmsImageUrl(url, transformParams);
+    const isAnimated = ANIMATED_EXT_REGEX.test(url);
+    const transformedPath = isAnimated ? url : getCmsImageUrl(url, transformParams);
     const href = transformedPath;
     const newImg = m[0].replace(rawSrc, transformedPath);
     const newBlock = `<a href="${href}" target="_blank" rel="noopener noreferrer" class="markdown-image-link">${newImg}</a>`;