Add the dualpath-as-single-machine site toggle

Most facilities consider a Dualpath pair one physical dual-bay machine.
New site setting dualpath_single_machine (default on): the machines
list, dashboard counts, machines-by-type report, and floor map collapse
each pair to its primary bay (lower assetnumber), with combined
2007 / 2008 labels; pagination totals stay honest. Detail pages remain
per-bay and always show a dual-bay sibling banner linking the partner.
Pair resolution lives in core services and joins the plugin contract
surface (0.8.0 -> 0.9.0).

On the WJ dataset: 31 pairs collapse, machine counts 262 -> 231, map
470 assets. Toggle verified live in both states, left on.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

shopdb/core/api/dashboard.py

@@ -19,10 +19,21 @@ _TYPE_CATEGORY = {
 
 
 def _count_by_type(assettype):
-    return db.session.query(Asset).join(AssetType).filter(
+    query = db.session.query(Asset).join(AssetType).filter(
         Asset.isactive == True,
         AssetType.assettype == assettype
-    ).count()
+    )
+    # Dualpath single-machine collapse: subtract the hidden secondary bays so a
+    # dual-bay machine counts once. Only machines are ever Dualpath-paired, but
+    # the AssetType filter above keeps this correct for any type. Default on.
+    if assettype == 'machine':
+        from shopdb.core.services.dualpath import (
+            resolve_dualpath_pairs, dualpath_single_machine_enabled)
+        if dualpath_single_machine_enabled():
+            secondaryassetids = resolve_dualpath_pairs().secondaryassetids
+            if secondaryassetids:
+                query = query.filter(Asset.assetid.notin_(secondaryassetids))
+    return query.count()
 
 
 @dashboard_bp.route('/summary', methods=['GET'])