feat: begin implementation of "sub tabs"

src/pages/student/additional_page.rs

@@ -0,0 +1,13 @@
+use leptos::prelude::*;
+
+#[component]
+pub fn AdditionalPage() -> impl IntoView {
+    view! {
+        <div class="flex flex-1 flex-col gap-4 items-center m-4">
+            <div class="font-bold text-3xl">"Student Additional Forms"</div>
+            <div class="text-lg">
+                "This is just a placeholder for now. We'll show redirect buttons to each form."
+            </div>
+        </div>
+    }
+}