frontend: separate files

frontend/src/components/pages/not_found.rs

@@ -0,0 +1,12 @@
+use yew::prelude::*;
+
+#[function_component(NotFound)]
+pub fn not_found() -> Html {
+    html!(
+        <div class="grid-cols-3 place-items-center">
+            <br/>
+            <h1 class="font-extrabold text-9xl">{"404"}</h1>
+            <span class="text-2xl font-normal">{"Не найдено"}</span>
+        </div>
+    )
+}