refactor(jobs): address code review feedback on fp.job (Task 1.4)

- Move NOTE comment from between @api.depends and the function
  into a proper docstring on _compute_costs.
- Make currency_id required=True (default still in place — only
  a programmatic write would null it, but Monetary fields need a
  non-null anchor).
- Add test_current_location_for_confirmed to cover the title-case
  fallback branch in _compute_current_location.

Manifest 19.0.8.3.0 → 19.0.8.3.1.

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/models/fp_job.py

@@ -122,6 +122,7 @@ class FpJob(models.Model):
     # ------------------------------------------------------------------
     currency_id = fields.Many2one(
         'res.currency',
+        required=True,
         default=lambda self: self.env.company.currency_id,
     )
     quoted_revenue = fields.Monetary(
@@ -141,9 +142,13 @@ class FpJob(models.Model):
     )
 
     @api.depends('quoted_revenue')
-    # NOTE: when fp.job.step lands in Task 1.5, this dependency expands
-    # to include 'step_ids.cost_total'. For now actual_cost is always 0.
     def _compute_costs(self):
+        """Cost rollup for the job header.
+
+        TODO(Task 1.5): when fp.job.step lands, expand @api.depends to
+        include 'step_ids.cost_total' so actual_cost rolls up
+        step time × work_centre.cost_per_hour automatically.
+        """
         for job in self:
             job.actual_cost = 0.0
             job.margin = job.quoted_revenue - job.actual_cost