feat(frontend): always show footer at bottom of page

frontend/src/routes/+layout.svelte

@@ -23,15 +23,20 @@
   <meta property="og:site_name" content="pronouns.cc" />
 </svelte:head>
 
-<Navigation />
-<div class="container">
+<div class="d-flex flex-column min-vh-100">
+  <div class="flex-grow-1">
+    <Navigation />
+    <div class="container">
       <slot />
       <div class="position-absolute top-0 end-0">
         {#each $toastStore as toast}
           <Toast header={toast.header} body={toast.body} />
         {/each}
       </div>
-  <footer>
+    </div>
+  </div>
+
+  <footer class="container">
     <hr />
     <p>
       pronouns.cc <a href="https://codeberg.org/u1f320/pronouns.cc/commit/{commit}">{version}</a>