feat(fusion_repairs): Bundle 5 - M5 pre-paid service plans + burn-down

New models
- fusion.repair.service.plan.subscription
  Tracks pre-paid maintenance packages: partner, plan product, optional
  category restriction, visits_included / visits_used / visits_remaining,
  start_date / end_date, computed state (active/exhausted/expired/cancelled),
  burn_history One2many. PLAN-NNNNN sequence.
- fusion.repair.service.plan.burn
  One row per maintenance visit that consumed a plan visit - feeds the
  Burn History tab on the subscription form.

product.template extensions
- x_fc_is_service_plan boolean toggle
- x_fc_plan_visits_included (default 4)
- x_fc_plan_duration_months (default 12)
- x_fc_plan_category_id - if set, only burns for repairs in that category
  (e.g. an Annual Stairlift Maintenance plan does not burn for wheelchair
  repairs)

sale.order.action_confirm() override
- For each order line whose product has x_fc_is_service_plan=True,
  spawns one fusion.repair.service.plan.subscription per qty unit.
- Start date = today; end date = today + plan_duration_months
  (relativedelta - correct month boundaries).

Visit report wizard
- New _burn_service_plan_visit(repair) call from action_confirm() finds
  the matching active subscription and burns one visit + posts a chatter
  note "Visit burned for repair X. N of M remaining." on the subscription.
- Skips quote-only repairs.
- The wizard does NOT zero out the invoice - the burn is informational;
  the office reconciles plan credits in their accounting workflow.

Backend
- Service Plans menu under Fusion Repairs root.
- List view colour-coded by state.
- Form with statusbar + cancel button + Burn History notebook.
- Service Plan tab added to product.template form (manager only).
- ACL: User read; Dispatcher write/create; Manager full + unlink.

Verified end-to-end on local westin-v19:
  Created plan product 'Annual Stairlift Maintenance - 4 Visits'
  Sold it via sale.order -> PLAN-00001 auto-created
  (visits_included=4, end_date=2027-05-21)
  Submitted visit-report on a stairlift repair -> visits_used=1
  remaining=3 (correctly category-matched).

Bumped to 19.0.1.5.0.

Co-authored-by: Cursor <cursoragent@cursor.com>

fusion_repairs/wizard/repair_visit_report_wizard.py

@@ -187,6 +187,14 @@ class RepairVisitReportWizard(models.TransientModel):
         if self.issue_inspection_cert:
             self._create_inspection_certificate(repair)
 
+        # M5: burn a pre-paid service plan visit if the client has one and
+        # the repair is a maintenance visit. The wizard intentionally does NOT
+        # zero out the client's invoice line - the office still posts the
+        # invoice; the burn is informational + the office reconciles credits
+        # in their accounting flow.
+        if not repair.x_fc_is_quote_only:
+            self._burn_service_plan_visit(repair)
+
         # If a stub was spawned, open it directly so the tech can fill in details.
         # Otherwise, if a certificate was issued, jump to it so the tech can print.
         if stub:
@@ -213,6 +221,14 @@ class RepairVisitReportWizard(models.TransientModel):
             'res_id': repair.id,
         }
 
+    def _burn_service_plan_visit(self, repair):
+        """M5: deduct one visit from the most-recently-active service plan
+        covering this repair. Quietly no-ops if the client has no plan."""
+        Plan = self.env['fusion.repair.service.plan.subscription'].sudo()
+        sub = Plan.find_for_repair(repair)
+        if sub:
+            sub.burn_visit(repair)
+
     def _create_inspection_certificate(self, repair):
         """M1: create the inspection certificate. Requires a safety-critical
         equipment category - otherwise just logs to chatter and skips."""