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_html.py

@@ -0,0 +1,22 @@
+# Render BoL HTML body to see the real error
+import traceback
+env = env  # noqa
+report = env.ref('fusion_plating_reports.action_report_fp_bol_portrait')
+dlv = env['fusion.plating.delivery'].search([], order='id desc', limit=1)
+print('rendering HTML for:', dlv.name, 'id=', dlv.id)
+try:
+    html, _ = report.with_context(force_report_rendering=True
+        )._render_qweb_html(report.report_name, [dlv.id])
+    out = html.decode() if isinstance(html, bytes) else str(html)
+    print('HTML length:', len(out))
+    # Show beginning + look for Traceback markers
+    if 'Traceback' in out or 'Oops' in out:
+        idx = max(out.find('Traceback'), out.find('Oops'))
+        print('--- ERROR SECTION ---')
+        print(out[idx:idx+3000])
+    else:
+        print('--- FIRST 800 CHARS ---')
+        print(out[:800])
+except Exception:
+    print('--- DIRECT EXCEPTION ---')
+    traceback.print_exc()