Resolve result images against an absolute baseUrl

Relative images were resolved against the page URL, but only the
pathname was kept, so with a baseUrl on another domain the image
still loaded from the search site. Keep the origin when the page URL
has one, in the Component UI's resolveUrl filter and in both Default
UI result templates. result_with_subs.svelte didn't resolve images at
all before.

Fixes #573

pagefind_ui/default/svelte/result_with_subs.svelte

@@ -10,6 +10,16 @@
   let non_root_sub_results = [];
   let has_root_sub_result = false;
 
+  const resolveImageUrl = (src, pageUrl) => {
+    if (!src || /^[a-z][a-z0-9+.-]*:/i.test(src) || /^\/\//.test(src)) return src;
+    try {
+      const url = new URL(src, new URL(pageUrl || "/", "https://p"));
+      return url.origin === "https://p" ? url.pathname + url.search + url.hash : url.href;
+    } catch {
+      return src;
+    }
+  };
+
   const thin_sub_results = (results, limit) => {
     if (results.length <= limit) {
       return results;
@@ -26,6 +36,9 @@
   const load = async (r) => {
     data = await r.data();
     data = process_result?.(data) ?? data;
+    if (data.meta?.image) {
+      data = { ...data, meta: { ...data.meta, image: resolveImageUrl(data.meta.image, data.meta.url || data.url) } };
+    }
     meta = Object.entries(data.meta).filter(([key]) => !skipMeta.includes(key));
     if (Array.isArray(data.sub_results)) {
       has_root_sub_result =