fix(quotesdb): home page friendly empty state when no quotes

Detect 404 from random quote endpoint and render a friendly
'Nothing here yet — Submit a quote!' message with a link to
/submit instead of the generic error display.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

quotesdb/src/bin/ui/pages/home.rs

@@ -1,6 +1,6 @@
 //! Home page — displays a random quote on load.
 
-use crate::api;
+use crate::api::{self, ApiError};
 use crate::components::error::ErrorDisplay;
 use crate::components::quote_card::QuoteCard;
 use crate::Route;
@@ -17,11 +17,13 @@ use yew_router::prelude::*;
 pub fn home_page() -> Html {
     let quote: UseStateHandle<Option<Quote>> = use_state(|| None);
     let error: UseStateHandle<Option<String>> = use_state(|| None);
+    let empty = use_state(|| false);
     let loading = use_state(|| true);
 
     {
         let quote = quote.clone();
         let error = error.clone();
+        let empty = empty.clone();
         let loading = loading.clone();
         use_effect_with((), move |_| {
             spawn_local(async move {
@@ -30,6 +32,10 @@ pub fn home_page() -> Html {
                         quote.set(Some(q));
                         loading.set(false);
                     }
+                    Err(ApiError::Server { status: 404, .. }) => {
+                        empty.set(true);
+                        loading.set(false);
+                    }
                     Err(e) => {
                         error.set(Some(e.to_string()));
                         loading.set(false);
@@ -46,6 +52,13 @@ pub fn home_page() -> Html {
 
             if *loading {
                 <p class="page-home__loading">{ "Loading..." }</p>
+            } else if *empty {
+                <div class="page-home__empty">
+                    <p>{ "Nothing here yet." }</p>
+                    <Link<Route> to={Route::Submit} classes="btn btn--primary">
+                        { "Submit a quote!" }
+                    </Link<Route>>
+                </div>
             } else if let Some(err) = (*error).clone() {
                 <ErrorDisplay message={err} />
             } else if let Some(q) = (*quote).clone() {