feat: implement AI bouquet generation flow with Gemini/OpenAI

* feat: scaffold message, generating, and map pages and align header steps

* feat: implement AI bouquet generation flow with Gemini/OpenAI

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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/lib/components/ui/Button.svelte

@@ -1,7 +1,7 @@
 <script>
-	let { children } = $props();
+	let { children, onclick = undefined } = $props();
 </script>
 
-<button class="bg-black px-6 py-3 text-white">
+<button class="bg-black px-6 py-3 text-white" {onclick}>
 	{@render children()}
 </button>