feat(image): enhance image handling with new properties and responsive support

- Updated PostEntry type to include _rawImageUrl and _imageFocal for improved image management.
- Refactored image handling in various components to utilize the new properties, ensuring better focal point support and responsive image rendering.
- Introduced warmResponsiveImage function for pre-fetching image variants to optimize loading performance.
- Replaced CmsImage component with RustyImage in multiple blocks for consistent image processing.

src/lib/components/blocks/ImageGalleryBlock.svelte

@@ -7,7 +7,8 @@
   import Icon from "@iconify/svelte";
   import { useTranslate } from "$lib/translations";
   import { T } from "$lib/translations";
-  import CmsImage from "$lib/components/CmsImage.svelte";
+  import RustyImage from "$lib/components/RustyImage.svelte";
+  import { extractCmsImageField } from "$lib/rusty-image";
 
   const t = useTranslate();
   let { block }: { block: ImageGalleryBlockData } = $props();
@@ -26,27 +27,24 @@
   const withUrl = $derived(
     images
       .map((img) => {
-        const url = imageUrl(img);
-        return url != null ? { img, url } : null;
+        const field = extractCmsImageField(img);
+        return field?.url
+          ? { img, url: field.url, focal: field.focal ?? null }
+          : null;
       })
-      .filter((x): x is { img: ImageGalleryImage; url: string } => x != null),
+      .filter(
+        (
+          x,
+        ): x is {
+          img: ImageGalleryImage;
+          url: string;
+          focal: { x: number; y: number } | null;
+        } => x != null,
+      ),
   );
 
   let currentIndex = $state(0);
 
-  function imageUrl(img: ImageGalleryImage): string | null {
-    if (typeof img.src === "string") {
-      const s = img.src.trim();
-      if (!s) return null;
-      return s.startsWith("//") ? `https:${s}` : s;
-    }
-    if (img.file?.url) {
-      const u = img.file.url;
-      return u.startsWith("//") ? `https:${u}` : u;
-    }
-    return null;
-  }
-
   function prev() {
     currentIndex = (currentIndex - 1 + withUrl.length) % withUrl.length;
   }
@@ -122,12 +120,12 @@
     <p class="text-sm text-stein-500">{t(T.image_gallery_empty)}</p>
   {:else if withUrl.length === 1}
     <figure class="m-0">
-      <CmsImage
+      <RustyImage
         src={withUrl[0].url}
+        focal={withUrl[0].focal}
         width={1280}
-        height={720}
+        aspect="16/9"
         fit="cover"
-        format="webp"
         quality={80}
         alt={withUrl[0].img.description ?? ""}
         class="w-full rounded-sm object-cover aspect-video"
@@ -158,12 +156,12 @@
             class="m-0 absolute inset-0"
             transition:fade={{ duration: 200 }}
           >
-            <CmsImage
+            <RustyImage
               src={current.url}
+              focal={current.focal}
               width={1280}
-              height={720}
+              aspect="16/9"
               fit="cover"
-              format="webp"
               quality={80}
               alt={current.img.description ?? ""}
               class="w-full h-full object-cover"