Tag material list by discipline for multi-discipline WPs

When a package carries 2+ disciplines, the BOM gains a per-line Discipline
column (hidden otherwise). Split by Discipline routes each instance only the
material lines tagged to it; untagged lines stay on the kept master, and the
split summary flags how many were untagged. Rendered doc shows the column
when any line is tagged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

wp-creation-index.html

@@ -114,7 +114,7 @@
   <div class="card">
     <div class="sub-heading">Material List</div>
     <div class="notice">Structured bill of materials. Feeds kitting and the delivery forecast. Unit is from the Acumatica unit list.</div>
-    <div class="table-wrap"><table><thead><tr><th style="width:90px">Qty</th><th style="width:120px">Unit</th><th>Description</th><th style="width:44px"></th></tr></thead><tbody id="material-body"></tbody></table></div>
+    <div class="table-wrap"><table><thead><tr><th style="width:90px">Qty</th><th style="width:120px">Unit</th><th>Description</th><th id="mat-disc-th" style="width:140px;display:none">Discipline</th><th style="width:44px"></th></tr></thead><tbody id="material-body"></tbody></table></div>
     <div class="material-actions">
       <button class="add-btn" onclick="addMaterial()">+ Add Material Line</button>
       <button class="add-btn" onclick="document.getElementById('material-import').click()">⤒ Import from Excel/CSV</button>