feat(jobs): add fp.job.step.timelog for granular timer tracking

Each button_start opens a fresh timelog row; button_finish closes
the open row and recomputes step.duration_actual as the sum of all
interval durations. Replicates Odoo MRP's mrp.workorder.time_ids
granularity natively (no mrp dep).

Schema: step_id (M2O cascade), user_id, date_started,
date_finished, duration_minutes (computed, stored).

ACLs: operator get create permission on timelogs because
button_start creates them.

Tests: test_start_creates_timelog (asserts the log row exists,
date_finished is False, user_id is the current user) and
test_finish_closes_timelog (asserts log gets date_finished, has a
non-negative duration, and step.duration_actual matches).

Manifest 19.0.8.5.1 -> 19.0.8.6.0.

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': '19.0.8.5.1',
+    'version': '19.0.8.6.0',
     'category': 'Manufacturing/Plating',
     'summary': 'Core plating / metal finishing ERP: facilities, processes, tanks, baths, jobs, operators.',
     'description': """