feat(ksef): print KSeF number + verification QR on invoice PDF

[hedon77]

Zmiana

Na PDF faktury (VAT) nanoszony jest numer KSeF i kod QR weryfikacji — wyłącznie, gdy moduł KSeF jest włączony i faktura została zaakceptowana w KSeF (ma \ksef_number). Na instalacjach bez KSeF nic się nie drukuje.

Szczegóły

• \Invoice::ksefInvoice()\ — nowa relacja \hasOne(KsefInvoice::class).
• \InvoicePdfService::ksefInfo()\ — zwraca {number, qr}\ albo
  ull:
  • warunek: \AddonManager::isActive('ksef')\ + niepusty \ksef_number,
  • QR = PNG data-URI wygenerowany przez \�acon/bacon-qr-code\ (GD), kodujący oficjalny URL weryfikacji \https://ksef.mf.gov.pl/web/verify?nr=…\ (dla integration/demo → \ksef-test),
  • generowanie w try/catch → awaria GD nigdy nie psuje PDF.
• 
  esources/views/pdf/invoice.blade.php\ — blok QR+numer po sumach, przed stopką.
• \pdf.ksef_number\ — tłumaczenie en/pl.

Weryfikacja

• Faktura z \ksef_number\ zwraca numer + QR PNG (data URI).
• Faktura bez KSeF zwraca
  ull\ (brak bloku).

[Panelica]

Merged — thank you, this is well guarded. The ksefInfo() gate (addon inactive or no ksef_number → returns null, nothing prints) means non-KSeF installs render invoices unchanged, and wrapping QR generation in catch (\Throwable) so a missing GD/BaconQrCode never breaks an invoice is the right instinct. bacon/bacon-qr-code ^3.0 is already in composer, and KsefInvoiceIssuedMail correctly reuses the LocalizesToRecipient trait from #26. Emailing the definitive PDF only after a KSeF number is issued is the correct trigger point. #29's footer change is folded in here as you noted.

Two things I completed on merge (follow-up 09b7c5c):

1. email.ksef_issued.* and pdf.ksef_number were en+pl only — added tr/zh (same parity/mirror reason as fix(dashboard): configured currency + localized widget labels #27).
2. EmailTemplateCoverageTest asserts every app/Mail/* mailable an operator can edit is bound to a template. KsefInvoiceIssuedMail isn't one of those — it renders its own fixed layout with the PDF + QR attached, like BulkMassMail — so I excluded it from that test with a comment, rather than forcing it into the template system.

Full suite green (2333 passing, only the two pre-existing environmental db-backup tests remain).