Fix transfer quantity, unify date format, align demo seeds

Stock Transfer list showed 0.00 (read in instead of out); stock-out/transfer forms show the location quantity; dates display as YYYY-MM-DD HH:mm:ss. Demo seeds map product accounts, use product names and supplier batches, and add demo_seed_assets.php.

app/order/manage_invoice.php

@@ -250,7 +250,7 @@
         $('#display_contact').text(inv.contact_name || '—');
         $('#display_department').text(get_dept_label(inv.department_id));
         $('#display_issued').text(format_date(inv.issued_date) || '—');
-        $('#due_date').val(inv.due_date ? format_date(inv.due_date) : '');
+        $('#due_date').val(inv.due_date ? format_date_input(inv.due_date) : '');
         $('#notes').val(inv.notes || '');
 
         var gl_type = inv.doc_type === 'credit_note' ? 'sales_credit_note' : 'sales_invoice';

app/order/manage_order.php

@@ -493,7 +493,7 @@
         // Fields
         $('#contact').val(o.contact_name || '');
         $('#contact_id').val(o.contact_id);
-        $('#order_date').val(o.order_date ? format_date(o.order_date) : '');
+        $('#order_date').val(o.order_date ? format_date_input(o.order_date) : '');
         $('#department_id').val(o.department_id || 0);
         $('#notes').val(o.notes || '');
         $('#discount').val(o.discount || 0);

app/order/manage_return.php

@@ -795,7 +795,7 @@
         $('#badge_status').html(return_status_badge(r.status));
         $('#return_number_display').text(r.return_number);
 
-        $('#return_date').val(r.return_date ? format_date(r.return_date) : '');
+        $('#return_date').val(r.return_date ? format_date_input(r.return_date) : '');
         $('#reason').val(r.reason || '');
         $('#tax_adjustment').val(parseFloat(r.tax_adjustment || 0).toFixed(2));
         $('#display_department').text(get_dept_label(r.department_id));