feat(process-repo): extender fromRow/toRow/getById con areaId y areaName

- fromRow: extrae areaId y areaName (vía JOIN en getById)
- toRow y updateEditable: incluyen area_id en escrituras a Supabase
- getById: JOIN con areas!area_id(name) para obtener nombre en una query
- Fixtures de tests actualizados con areaId: null (campo requerido)
- 4 tests nuevos en tests/persistence/area-repo.test.ts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/lib/export/pdf-scenario-page1.test.ts

@@ -52,7 +52,7 @@ const mockProcess: Process = {
   bpmnXml: '', currency: 'USD', overheadPercentage: 0.2,
   annualFrequency: 5000, analysisHorizonYears: 3, automationInvestment: 80000,
   createdAt: 0, updatedAt: 0,
-  groupId: null, tags: [], ownerId: 'test-user', updatedBy: 'test-user', orgId: null,
+  groupId: null, tags: [], ownerId: 'test-user', updatedBy: 'test-user', orgId: null, areaId: null,
 }
 
 const mockSimulation: Simulation = {