fix: add html,body height:100% to match Material layout

Material's all-component-themes mixin sets height: 100% on html and body
for the sidenav/toolbar layout. Without it, fullPage screenshots capture
the full content height instead of the viewport, causing 4-5x height diffs.

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

Author: chrisjwalk-bot

apps/web-app/src/styles/styles.css

@@ -89,6 +89,11 @@
     border-color: var(--color-gray-200, currentColor);
   }
 
+  html,
+  body {
+    height: 100%;
+  }
+
   html {
     font-display: swap;
     font-size: 14px; /* Material base: 1rem = 14px */