feat: update layout and styling, extend memorial page content

Enhanced layout snippet with conditional styling support for dark mode. Updated typography and grid classes for improved text and visual consistency. Added additional memorial section content, including headings and text fields for tributes. Expanded blueprint definitions with new block types (`line`, `gallery`, and `quote`). Adjusted chessboard piece and square dimensions in `pgn4web.css` for refined appearance.

site/templates/blockpage.php

@@ -24,8 +24,8 @@ function fenToBoard($fen) {
 
 <?php
 snippet('layout', slots: true) ?>
-
-    <?= $page->blocks()->toBlocks() ?>
-
+    <div class="blockpage">
+        <?= $page->blocks()->toBlocks() ?>
+    </div>
 <?php
 endsnippet() ?>

site/templates/impressum.php

@@ -1,7 +1,7 @@
 <?php snippet('layout', slots: true) ?>
 
 <section class="bg-sf_grau-50 py-24">
-    <div class="lg:px-8 max-w-7xl mx-auto px-4 sm:px-6">
+    <div class="impressum lg:px-8 max-w-7xl mx-auto px-4 sm:px-6">
         <h1 class="text-3xl">Impressum</h1>
     </div>
     <div class="grid grid-cols-1 lg:grid lg:grid-cols-2 lg:px-8 max-w-7xl mx-auto px-4 sm:px-6">