Add visual spool grouping and optional brand/subtype in quick-add (#480)

Group toggle in inventory toolbar collapses identical unused/unassigned
spools into expandable rows/cards with count badges. Grouping key uses
material, subtype, brand, color, and label weight. Brand and subtype
fields now appear in quick-add mode as optional (no asterisk, no
validation). Quantity field restricted to quick-add mode only.

static/index.html

@@ -23,8 +23,8 @@
 
     <!-- Splash screens for iOS -->
     <link rel="apple-touch-startup-image" href="/img/android-chrome-512x512.png" />
-    <script type="module" crossorigin src="/assets/index-BG7oML9S.js"></script>
-    <link rel="stylesheet" crossorigin href="/assets/index-DJax8qcY.css">
+    <script type="module" crossorigin src="/assets/index-DmRt97yN.js"></script>
+    <link rel="stylesheet" crossorigin href="/assets/index-DlQCzTdY.css">
   </head>
   <body>
     <div id="root"></div>