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/index.html

@@ -536,8 +536,6 @@
                 </div>
                 <button class="copy-table-btn no-copy" onclick="resetCustomColumns()" style="white-space:nowrap;">Reset Columns</button>
                 <button class="copy-table-btn no-copy" onclick="shrinkCustomColumns()" style="white-space:nowrap;">Shrink Widths</button>
-                <button class="copy-table-btn no-copy" onclick="resetCustomFilters()" style="white-space:nowrap;">Reset Filters</button>
-                <button class="copy-table-btn no-copy" onclick="resetCustomSort()" style="white-space:nowrap;">Reset Sort</button>
             </div>
 
             <div class="table-wrapper" id="wrapper-custom" style="background: var(--bg-card); border-radius: 8px; box-shadow: 0 4px 6px rgba(0,0,0,0.3); overflow: hidden;">