Filter menus: None first, documented picks; Custom View drag preview

- Fix: sorting a software column stopped its filter listing apps
  individually (the sort arrow written into the header changed the label
  used to recognise list columns)
- "None" (nothing missing) is pinned to the top of the value list, so the
  easy devices are one click away
- Software columns get "Documented" / "Undocumented" quick picks that
  tick only apps with / without a knowledge-base article; documented apps
  are marked in the list
- Custom View: remove Reset Filters / Reset Sort (Clear filters and the
  column menus replace them); old saved filters are cleared since nothing
  else could clear them
- Custom View column drag: a ghost of the column follows the cursor, the
  column being moved is dimmed, and a line shows where it will land

web/layout.css

@@ -344,3 +344,38 @@ table.xf-table thead th:has(> .xf-btn):not(.sortable-th) { position: relative; p
 .xf-addfield[hidden] { display: none; }
 .xf-clear-all { white-space: nowrap; color: #f1c40f !important; border-color: rgba(241,196,15,0.6) !important; }
 .xf-clear-all svg { width: 14px; height: 14px; flex: none; }
+
+/* Software menus: documented / undocumented quick picks, doc marker, "None" pinned first */
+.xf-picks { display: flex; gap: 6px; padding: 0 12px 6px; }
+.xf-pick {
+    flex: 1; padding: 5px 6px; cursor: pointer; font: inherit; font-size: 0.82em; white-space: nowrap;
+    background: transparent; color: #3498db; border: 1px solid rgba(52,152,219,0.55); border-radius: 5px;
+}
+.xf-pick:hover:not(:disabled) { background: rgba(52,152,219,0.12); }
+.xf-pick:disabled { opacity: 0.4; cursor: default; }
+.xf-opt.xf-doc span::after {
+    content: ''; display: inline-block; width: 9px; height: 11px; margin-left: 6px; vertical-align: -1px;
+    border: 1.5px solid #3498db; border-radius: 1.5px; box-sizing: border-box;
+    background: linear-gradient(#3498db, #3498db) 2px 3px / 3px 1.5px no-repeat,
+                linear-gradient(#3498db, #3498db) 2px 6px / 3px 1.5px no-repeat;
+}
+.xf-opt.xf-none { font-style: italic; border-bottom: 1px dashed var(--border-light); }
+
+/* Custom View column drag preview (layout.js) */
+.col-drag-ghost {
+    position: fixed; top: -1000px; left: -1000px; z-index: 9999; pointer-events: none;
+    background: var(--bg-card); color: var(--text-main); border: 2px solid #3498db; border-radius: 6px;
+    box-shadow: 0 10px 24px rgba(0,0,0,0.45); overflow: hidden; font-size: 12px;
+}
+.col-drag-ghost-head { padding: 7px 10px; font-weight: 700; color: #fff; background: var(--table-header-bg); }
+.col-drag-ghost-cell {
+    padding: 5px 10px; border-top: 1px solid var(--border-light);
+    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
+}
+#table-custom .col-moving { opacity: 0.35; }
+.col-drop-marker {
+    position: absolute; top: 0; width: 4px; z-index: 30; pointer-events: none;
+    background: #3498db; border-radius: 2px; box-shadow: 0 0 8px rgba(52,152,219,0.8);
+}
+/* the single insertion line replaces the per-header highlight */
+#table-custom .custom-th.drag-over { box-shadow: none !important; }