refacto: move home code into a dedicated file and rename index to home everywhere

crates/app/src/pages/home.rs

@@ -0,0 +1,12 @@
+use askama_axum::Template;
+use axum_htmx::HxRequest;
+
+#[derive(Template)]
+#[template(path = "home.html")]
+pub struct GetHomeTemplate {
+    hx_request: bool,
+}
+
+pub async fn home(HxRequest(hx_request): HxRequest) -> GetHomeTemplate {
+    GetHomeTemplate { hx_request }
+}