feat: wire Zod validation into API routes, improve types and components

- Add 8 new Zod schemas (UpdateCustomer, UpdateSupplier, UpdateSupplierInvoice,
  UpdateAccount, BankUnlink, RunReconciliation, CorrectJournalEntry,
  EvaluateMappingRules) and wire validateBody() into 24 JSON-body API routes
- Remove redundant manual validation checks replaced by Zod
- Add comprehensive schema tests (222 tests)
- Improve type definitions in types/index.ts with expanded interfaces
- Refactor extension types (push-notifications, receipt-ocr) for cleaner imports
- Update transaction components (BatchCategorySelector, SwipeCategorizationView,
  QuickReviewDialog, VatTreatmentSelect) and invoice inbox workspace
- Add invoice-inbox utilities and type decoupling tests
- Fix NE-bilaga, SRU export, and invoice PDF template type usage
- Update CLAUDE.md with expanded architecture documentation

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

app/api/deadlines/route.ts

@@ -1,6 +1,7 @@
 import { createClient } from '@/lib/supabase/server'
 import { NextResponse } from 'next/server'
-import type { CreateDeadlineInput } from '@/types'
+import { validateBody } from '@/lib/api/validate'
+import { CreateDeadlineSchema } from '@/lib/api/schemas'
 
 /**
  * GET /api/deadlines
@@ -78,12 +79,9 @@ export async function POST(request: Request) {
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
-  const body: CreateDeadlineInput = await request.json()
-
-  // Validate required fields
-  if (!body.title || !body.due_date || !body.deadline_type) {
-    return NextResponse.json({ error: 'Missing required fields' }, { status: 400 })
-  }
+  const validation = await validateBody(request, CreateDeadlineSchema)
+  if (!validation.success) return validation.response
+  const body = validation.data
 
   // Insert the deadline
   const { data, error } = await supabase