fix(reports): collapse sig-row to one bordered table — kill duplicate borders

User reported "multiple unwanted vertical lines in the boxes" on the
portrait BoL. Pixel analysis confirmed it: previous design had 3
separate `<div class="sig-box">` each with its own 1px border, with a
4-8px gap between adjacent boxes — visually those adjacent borders
read as a doubled / "duplicate" line between cells.

Fix: replace 3-box layout with a single `<table class="bordered
sig-table">` containing 3 td cells. With border-collapse: collapse,
adjacent cells share their border — so the row now shows 4 vertical
lines (1 outer left + 2 internal dividers + 1 outer right) instead
of 6 close-together border lines.

- Dropped `.sig-box` class entirely (no per-box border anymore)
- Added `.sig-table` + `.sig-cell` with explicit 1px borders so the
  layout works without depending on `.bordered` class inheritance
- Applied to both portrait + landscape variants
- Landscape sig-row was still using the OLD Bootstrap row+col-4
  layout (never got replaced earlier) — also migrated to the new
  table layout

Verified: page count unchanged (portrait 1, landscape 1), all
labels and content present, structure clean.

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': '19.0.4.5.0',
+    'version': '19.0.4.7.0',
     'category': 'Manufacturing/Plating',
     'summary': 'PDF reports for Fusion Plating: quote, SO, WO, packing, BoL, CoC, invoice, receipt, quality + compliance.',
     'depends': [