feat: Add layout max-width for better UX on wide screens (#4)

Changes:
- Add 1400px max-width container in SpoolmanLayout
- Add 800px max-width for forms via CSS override

This prevents the UI from feeling too spread out on wide monitors
and MacBooks, improving readability and reducing eye movement.

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

client/src/utils/overrides.css

@@ -1,3 +1,8 @@
 #qty-input {
   text-align: center !important;
 }
+
+/* Constrain form width for better readability on wide screens */
+.ant-form {
+  max-width: 800px;
+}