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>

src/features/import/ImportPage.tsx

@@ -92,6 +92,7 @@ export function ImportPage() {
         ownerId: user!.id,
         updatedBy: user!.id,
         orgId: null,
+        areaId: null,
       }
 
       const activityElements = extractActivityElements(graph)

src/persistence/supabase/process-repo.ts

@@ -13,6 +13,7 @@ function toRow(process: Process, userId: string) {
     analysis_horizon_years: process.analysisHorizonYears,
     automation_investment: process.automationInvestment,
     group_id: process.groupId,
+    area_id: process.areaId,
     tags: process.tags,
     // owner_id se preserva del valor existente en el proceso; solo se inicializa con userId en creates
     owner_id: process.ownerId || userId,
@@ -25,6 +26,8 @@ function toRow(process: Process, userId: string) {
 function fromRow(row: Record<string, unknown>): Process {
   // org puede estar presente si el query hizo JOIN con organizations (getById lo incluye)
   const org = row.org as { name: string } | null
+  // area puede estar presente si el query hizo JOIN con areas (getById lo incluye)
+  const area = row.area as { name: string } | null
   return {
     id: row.id as string,
     name: row.name as string,
@@ -43,6 +46,8 @@ function fromRow(row: Record<string, unknown>): Process {
     updatedBy: (row.updated_by as string) ?? '',
     orgId: (row.org_id as string | null) ?? null,
     orgName: org?.name ?? null,
+    areaId: (row.area_id as string | null) ?? null,
+    areaName: area?.name ?? null,
   }
 }
 
@@ -91,6 +96,7 @@ export const supabaseProcessRepo = {
         automation_investment: process.automationInvestment,
         tags: process.tags,
         group_id: process.groupId,
+        area_id: process.areaId,
         updated_by: userId,
         updated_at: new Date().toISOString(),
       })
@@ -102,7 +108,7 @@ export const supabaseProcessRepo = {
     // JOIN con organizations para obtener orgName en una sola query (evita fetch separado y race conditions)
     const { data, error } = await supabase
       .from('processes')
-      .select('*, org:organizations!org_id(name)')
+      .select('*, org:organizations!org_id(name), area:areas!area_id(name)')
       .eq('id', id)
       .single()
     if (error) return undefined