Fix browse patterns grid layout - remove width constraint

Remove max-w-[680px] that was constraining the grid to a narrow width.
Update responsive columns: 3 → 4 → 5 → 6 → 7 across breakpoints.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

templates/index.html

@@ -259,7 +259,7 @@
         </div>
     </div>
     <section class="px-4 py-6">
-        <div class="grid grid-cols-3 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-5 gap-4 sm:gap-5 md:gap-6 max-w-[680px] mx-auto">
+        <div class="grid grid-cols-3 sm:grid-cols-4 md:grid-cols-5 lg:grid-cols-6 xl:grid-cols-7 gap-4 sm:gap-5 md:gap-6">
             <!-- All patterns will be populated here -->
         </div>
         <!-- Spacer to allow scrolling past last patterns -->