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/scripts/fp_bol_stress.py

@@ -0,0 +1,33 @@
+# Stress-test the BoL with progressively longer notes
+env = env  # noqa
+import re
+rep = env.ref('fusion_plating_reports.action_report_fp_bol_landscape')
+dlv = env['fusion.plating.delivery'].search([], order='id desc', limit=1)
+orig_notes = dlv.notes
+print(f'baseline (current notes={len(orig_notes or "") } chars)')
+
+scenarios = [
+    ('empty notes',     '',                               1),
+    ('one short line',  '<p>Handle with care.</p>',      1),
+    ('three lines',     '<p>Line 1</p><p>Line 2</p><p>Line 3</p>',  1),
+    ('ten lines',       ''.join(f'<p>Special instruction line {i}: handle with care, fragile, do not stack.</p>' for i in range(10)), 1),
+    ('paragraph block', '<p>' + ('Long instructions filling the cargo description box. ' * 30) + '</p>',  1),
+    ('huge block',      '<p>' + ('Very long instructions. ' * 80) + '</p>',  1),
+]
+print(f'\n{"scenario":<22} {"chars":<8} {"pages":<6}  signature row intact?')
+print('-' * 70)
+for label, notes, _ in scenarios:
+    dlv.write({'notes': notes})
+    pdf, _e = rep.with_context(force_report_rendering=True
+        )._render_qweb_pdf(rep.report_name, [dlv.id])
+    n_pages = len(re.findall(rb'/Type\s*/Page[^s]', pdf))
+    # Save last for inspection
+    with open(f'/tmp/bol_stress_{label.replace(" ","_")}.pdf', 'wb') as f:
+        f.write(pdf)
+    # Quick "intact" heuristic: if it's >1 page and the size is small,
+    # likely overflowed. Real check is in pypdf locally.
+    print(f'{label:<22} {len(notes):<8} {n_pages:<6}  (PDF saved)')
+
+# Restore
+dlv.write({'notes': orig_notes or False})
+print('\noriginal notes restored')