Stage 9 — Subcontractor System: outsourced work with cost+markup

Schema:
- subcontractors (specialty, rating, contact)
- subcontract_jobs (work_order link, cost, markup_pct, client_price, status
  workflow, sent_at/eta/returned_at, paid_to_sub)

Models:
- SubcontractJob: auto number (SC-YY-NNNN), client_price = cost×(1+markup/100)
  when markup>0 (else manual), margin() helper, recalcs parent WO on save/delete
- WorkOrder.recalcTotal now includes non-cancelled subcontract job client_price

Filament (new "Subcontractare" nav group):
- SubcontractorResource (specialty/rating CRUD)
- SubcontractJobResource board with cost/client/margin columns + status filters,
  nav badge = open jobs
- SubcontractJobsRelationManager on WorkOrder

Tests (7 new):
- client_price from markup; manual price without markup; auto number;
  WO total includes jobs; cancelled excluded; delete recalcs; tenant isolation

Closes roadmap to 16/18 stages (only Stage 10 Bodyshop remains).

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

app/Filament/Tenant/Resources/WorkOrderResource.php

@@ -214,6 +214,7 @@ class WorkOrderResource extends Resource
         return [
             RelationManagers\WorksRelationManager::class,
             RelationManagers\PartsRelationManager::class,
+            RelationManagers\SubcontractJobsRelationManager::class,
             RelationManagers\PaymentsRelationManager::class,
         ];
     }