fix(ux): prevent iOS auto-zoom on inputs + lazy-load page CSS

Increase font-size to 16px on mobile for shopping quick-add inputs,
notes search, and contacts search. Desktop breakpoint restores compact
sizes. Move 9 page-specific stylesheets from index.html to on-demand
loading in router.js, reducing initial CSS payload.

public/styles/notes.css

@@ -68,7 +68,7 @@
   border-radius: var(--radius-md);
   background: var(--color-surface);
   color: var(--color-text);
-  font-size: var(--text-sm);
+  font-size: var(--text-md);
   outline-offset: 2px;
 }
 
@@ -77,6 +77,10 @@
   border-color: transparent;
 }
 
+@media (min-width: 1024px) {
+  .notes-toolbar__search-input { font-size: var(--text-sm); }
+}
+
 /* --------------------------------------------------------
  * Masonry-Grid
  * -------------------------------------------------------- */