fix(reports): BoL PDF — t-field needs dotted path, branch on delivery_address_id

The Bill of Lading template assigned a temp variable
`<t t-set="dest" t-value="doc.delivery_address_id or doc.partner_id"/>`
and then tried `<div t-field="dest" .../>`. Odoo 19 QWeb asserts
t-field must be `record.field_name` (have a dot) — the temp variable
form fails compilation and the report renders as a multi-page
"Oops! Something went wrong" PDF stuffed with the traceback.

Fix: branch with `t-if`/`t-else` and call `t-field="doc.delivery_address_id"`
or `t-field="doc.partner_id"` directly. Same pattern in both header
and second-page-header sections (lines 49/235).

Verified: BoL render goes from 39 KB error page to 138 KB clean PDF.

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

fusion_plating/scripts/fp_bol_repro.py

@@ -0,0 +1,14 @@
+# Reproduce BoL render error
+import traceback
+env = env  # noqa
+report = env.ref('fusion_plating_reports.action_report_fp_bol_portrait')
+print('report:', report.report_name, 'model:', report.model)
+dlv = env['fusion.plating.delivery'].search([], order='id desc', limit=1)
+print('rendering for:', dlv.name, 'id=', dlv.id, 'state=', dlv.state)
+try:
+    pdf, _ = report.with_context(force_report_rendering=True
+        )._render_qweb_pdf(report.report_name, [dlv.id])
+    print('OK pdf size:', len(pdf), 'bytes')
+except Exception:
+    print('--- TRACEBACK ---')
+    traceback.print_exc()