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/settings/route.ts

@@ -1,6 +1,8 @@
 import { createClient } from '@/lib/supabase/server'
 import { NextResponse } from 'next/server'
 import { didTaxFieldsChange, regenerateTaxDeadlinesForUser } from '@/lib/tax/deadline-generator'
+import { validateBody } from '@/lib/api/validate'
+import { UpdateSettingsSchema } from '@/lib/api/schemas'
 
 export async function GET() {
   const supabase = await createClient()
@@ -40,7 +42,9 @@ export async function PUT(request: Request) {
     .eq('user_id', user.id)
     .single()
 
-  const body = await request.json()
+  const validation = await validateBody(request, UpdateSettingsSchema)
+  if (!validation.success) return validation.response
+  const body = validation.data
 
   // Validate: enskild firma must use calendar year (BFL 3 kap.)
   const effectiveEntityType = body.entity_type || oldSettings?.entity_type