feat(webui): "Last searched" options in header

webui/src/components/layout/Header.svelte

@@ -19,15 +19,36 @@
 
   let selector: Selector;
 
+  let lastSearched: SelectorValue[] = [];
+
+  function addLastSearched(value: SelectorValue) {
+    switch (value.t) {
+      case "Address":
+        lastSearched = lastSearched.filter(
+          (v) => v.t !== "Address" || v.c !== value.c,
+        );
+        break;
+      case "Attribute":
+        lastSearched = lastSearched.filter(
+          (v) => v.t !== "Attribute" || v.name !== value.name,
+        );
+        break;
+    }
+    lastSearched.unshift(value);
+    lastSearched = lastSearched.slice(0, 10);
+  }
+
   async function onInput(event: CustomEvent<SelectorValue>) {
     const value = event.detail;
     if (!value) return;
 
     switch (value.t) {
       case "Address":
+        addLastSearched(value);
         navigate(`/browse/${value.c}`);
         break;
       case "Attribute":
+        addLastSearched(value);
         {
           const attributeAddress = await api.componentsToAddress({
             t: "Attribute",
@@ -74,7 +95,7 @@
       placeholder={$i18n.t("Search or add")}
       on:input={onInput}
       bind:this={selector}
-      emptyOptions={[]}
+      emptyOptions={lastSearched}
     >
       <Icon name="search" slot="prefix" />
     </Selector>