added a welcome window

src/routes/welcome/+page.svelte

@@ -0,0 +1,40 @@
+<script lang="ts">
+  import { invoke } from "@tauri-apps/api/core";
+  import { getCurrentWebviewWindow } from "@tauri-apps/api/webviewWindow";
+
+  let isContinuing = false;
+
+  const handleContinue = async () => {
+    if (isContinuing) return;
+    isContinuing = true;
+    try {
+      await invoke("start_auth_flow");
+      await getCurrentWebviewWindow().close();
+    } catch (error) {
+      console.error("Failed to start auth flow", error);
+      isContinuing = false;
+    }
+  };
+</script>
+
+<div class="w-full h-full bg-base-100 flex items-center justify-center p-8">
+  <div class="card w-full max-w-md bg-base-200 shadow-lg">
+    <div class="card-body gap-4">
+      <div class="flex flex-col gap-1">
+        <h1 class="text-2xl font-semibold">Friendolls</h1>
+        <p class="text-base text-base-content/80">
+          Passive social app connecting peers through mouse cursor interactions in the form of desktop pets.
+        </p>
+      </div>
+      <div class="card-actions justify-end pt-2">
+        <button class="btn btn-primary" onclick={handleContinue} disabled={isContinuing}>
+          {#if isContinuing}
+            Loading...
+          {:else}
+            Continue
+          {/if}
+        </button>
+      </div>
+    </div>
+  </div>
+</div>