feat(jobs): persist deadlines + planned start + notes on fp.job

Tier 2 of the SO->fp.job persistence audit. Four operational metadata
fields mirrored from sale.order:

- x_fc_internal_deadline (Date) - shop's internal target finish date,
  ahead of the customer-facing deadline. Kept separate from
  date_deadline (which scheduling code may adjust).
- x_fc_planned_start_date (Date) - customer-quoted planned start date.
  Kept separate from date_planned_start (Datetime, capacity-adjusted).
- x_fc_internal_note (Text) - shop-internal notes from the order.
- x_fc_external_note (Text) - customer-facing notes, printed on
  traveller / BoL / cert.

All four populate at SO confirm via _fp_auto_create_job, and surface
on sale.order.line as stored related fields for per-line visibility.
fp.job form view gets a Notes group alongside the Customer References
group from Tier 1.

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

fusion_plating/fusion_plating/__manifest__.py

@@ -5,7 +5,7 @@
 
 {
     'name': 'Fusion Plating',
-    'version': '19.0.18.15.6',
+    'version': '19.0.18.15.7',
     'category': 'Manufacturing/Plating',
     'summary': 'Core plating / metal finishing ERP: facilities, processes, tanks, baths, jobs, operators.',
     'description': """