added Dart to the api preview examples

ui/src/components/collections/docs/SdkTabs.svelte

@@ -0,0 +1,55 @@
+<script>
+    import CodeBlock from "@/components/base/CodeBlock.svelte";
+
+    const SDK_PREFERENCE_KEY = "pb_sdk_preference";
+
+    export let js = "";
+    export let dart = "";
+
+    let activeTab = localStorage.getItem(SDK_PREFERENCE_KEY) || "javascript";
+
+    $: if (activeTab) {
+        // store user preference
+        localStorage.setItem(SDK_PREFERENCE_KEY, activeTab);
+    }
+
+    $: sdkExamples = [
+        {
+            title: "JavaScript",
+            language: "javascript",
+            content: js,
+        },
+        {
+            title: "Dart",
+            language: "dart",
+            content: dart,
+        },
+    ];
+</script>
+
+<div class="tabs sdk-tabs m-b-lg">
+    <div class="tabs-header compact left">
+        {#each sdkExamples as example (example.language)}
+            <button
+                class="tab-item"
+                class:active={activeTab === example.language}
+                on:click={() => (activeTab = example.language)}
+            >
+                <div class="txt">{example.title}</div>
+            </button>
+        {/each}
+    </div>
+    <div class="tabs-content">
+        {#each sdkExamples as example (example.language)}
+            <div class="tab-item" class:active={activeTab === example.language}>
+                <CodeBlock language={example.language} content={example.content} />
+            </div>
+        {/each}
+    </div>
+</div>
+
+<style>
+    .sdk-tabs .tabs-header .tab-item {
+        min-width: 100px;
+    }
+</style>