Add bulk editing to inventory tab with atomic batch API

Multi-select inventory items via checkboxes (select-all, shift-click
range, group header select) and apply bulk actions through a floating
toolbar: edit fields (shop, bin, price, THC/CBD), consume, checkout,
check in, and mark gone. Backend processes all operations in a single
SQLite transaction for atomicity.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/styles/global.css

@@ -105,12 +105,16 @@
   from { transform: translateX(100%); }
   to   { transform: translateX(0); }
 }
+@keyframes toolbar-slide-up {
+  from { transform: translateY(100%); opacity: 0; }
+  to   { transform: translateY(0); opacity: 1; }
+}
 
 @media (max-width: 1200px) {
-  .inv-row > :nth-child(4),
-  .inv-header > :nth-child(4) { display: none; } /* Shop */
-  .inv-row > :nth-child(8),
-  .inv-header > :nth-child(8) { display: none; } /* Last checked */
+  .inv-row > :nth-child(5),
+  .inv-header > :nth-child(5) { display: none; } /* Shop (shifted +1 by checkbox col) */
+  .inv-row > :nth-child(9),
+  .inv-header > :nth-child(9) { display: none; } /* Last checked */
 }
 
 @media (max-width: 880px) {
@@ -156,4 +160,8 @@
   .main {
     padding-bottom: 60px;
   }
+  .bulk-toolbar {
+    left: 0 !important;
+    bottom: 60px !important;
+  }
 }