fix(reports): keep BoL signature row intact across page breaks

Landscape BoL was splitting the signature row down the middle —
boxes half on page 1, half on page 2. Two complementary fixes:

1. **Per-element rule**: added `page-break-inside: avoid` +
   `break-inside: avoid` to `.sig-box` (both portrait + landscape
   styles) so an individual signature box can never split across
   pages.

2. **Wrapper rule**: introduced `.fp-keep-together` utility +
   wrapped the BoL's certification statement + signature row in
   it, so the whole "sign here" block moves to the next page as
   one unit if it doesn't fit. Also applied
   `page-break-inside: avoid` to `table tr` so cargo lines don't
   split mid-row either.

Lives in shared `report_base_styles.xml` so any FP template that
opts into `.fp-keep-together` benefits automatically.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_reports/__manifest__.py

@@ -3,7 +3,7 @@
 # License OPL-1 (Odoo Proprietary License v1.0)
 {
     'name': 'Fusion Plating — Reports',
-    'version': '19.0.4.2.0',
+    'version': '19.0.4.3.0',
     'category': 'Manufacturing/Plating',
     'summary': 'PDF reports for Fusion Plating: quote, SO, WO, packing, BoL, CoC, invoice, receipt, quality + compliance.',
     'depends': [