feat(jobs): add equipment, audit, plating-spec fields to fp.job.step

Equipment: bath_id, tank_id, rack_id (all in core). oven_id deferred
to a bridge module — fusion.plating.bake.oven lives in shopfloor and
core can't depend on it. masking_material_id deferred too — model
fusion.plating.masking.material does not yet exist anywhere; will be
added when the masking model lands.

Audit: signoff_user_id (readonly), facility_id (related from
work_centre_id, stored).

Plating spec: thickness_target, thickness_uom (um/mil/in),
dwell_time_minutes, bake_setpoint_temp, bake_actual_duration,
bake_chart_recorder_ref (Nadcap audit trail).

Recipe-related: requires_signoff, auto_complete, is_manual,
customer_visible (all related from recipe_node_id, stored, so
operator sees current values without re-querying process.node).

Cost rollup: cost_per_hour related from work_centre_id, cost_total
computed (duration_actual / 60 x rate), currency_id related too.
Full rollup-from-timelogs lands in Task 1.7.

Tests cover: facility_id related-field, thickness_uom default,
cost_total zero/non-zero paths.

Manifest 19.0.8.4.1 -> 19.0.8.5.0.

Part of: native job model migration (spec 2026-04-25)
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': '19.0.8.4.1',
+    'version': '19.0.8.5.0',
     'category': 'Manufacturing/Plating',
     'summary': 'Core plating / metal finishing ERP: facilities, processes, tanks, baths, jobs, operators.',
     'description': """