Fix/supp ag fb (#1023)

* fix: prevent credit notes from entering payment flow

* fix: persist and display customer personal numbers

* feat: configure automatic invoice reminder days

* fix: issue credit notes through send flow

* chore: add repository agent guidance

* feat(mcp): route tools across user companies

* fix(articles): delete unused register entries

* feat(invoices): improve issued invoice actions

* feat(supplier-invoices): retain uploaded source documents

* docs: record implementation decisions

* feat: enhance customer personal number handling and validation

- Updated CustomerForm to allow personal numbers in the format of "********-1234" for individual customers.
- Added validation to ensure personal numbers are only accepted for individual customers in CreateCustomerSchema.
- Implemented masking and encryption for personal numbers to enhance data protection.
- Introduced new utility functions for masking and encrypting personal numbers.
- Added database migration to enforce unique constraints on credit note relationships and prevent duplicate entries.
- Enhanced error handling and logging for credit note issuance and invoice processing.
- Updated tests to cover new credit note creation guards and personal number handling.

* test: enhance list companies test with supabase query mocks

lib/core/bookkeeping/__tests__/journal-entry-references.test.ts

@@ -52,6 +52,23 @@ describe('getJournalEntryUnderlagReferences', () => {
     expect(refs).toEqual([{ type: 'supplier_invoice', id: 'si-1', number: 'LF-001' }])
   })
 
+  it('surfaces the retained PDF through a supplier payment reference', async () => {
+    const refs = await run([
+      { data: [] }, // 1. invoices direct
+      { data: [] }, // 2. invoice_payments
+      { data: [] }, // 4. supplier registration
+      { data: [{ id: 'si-1', supplier_invoice_number: 'LF-001', document_id: 'doc-1' }] }, // 5. supplier payment
+      { data: [{ supplier_invoice_id: 'si-1' }] }, // 6. supplier_invoice_payments
+    ])
+
+    expect(refs).toEqual([{
+      type: 'supplier_invoice',
+      id: 'si-1',
+      number: 'LF-001',
+      document_id: 'doc-1',
+    }])
+  })
+
   it('returns nothing when no invoice is linked (warning legitimately stays)', async () => {
     const refs = await run([
       { data: [] }, // 1. invoices direct