feat(accounting): incoming-invoice triage refinements (paid badge, click-to-categorize, reference, categorize+pay)

#1 Row status reads 'Paid' (green) once supplierPaid — no longer the stale
   'categorized' badge.
#2 Clicking a new (unsorted) invoice opens the Categorize modal; sorted ones
   still open the read-only view.
#3 Triage gains a Payment reference field (persisted via updateInbound →
   payment_reference).
#5 Triage has two actions: 'Save' (categorize only) and 'Save & mark paid'
   (categorize, then chain into the mark-paid dialog with the reference
   prefilled).
#4 (mark-paid PDF nav) was already present via DocumentPreview — no change.

en/de strings added.

frontend/src/i18n/locales/de.json

@@ -3502,6 +3502,7 @@
       "categorizedToast": "Dokument kategorisiert.",
       "triageTitle": "Dokument kategorisieren",
       "saveCategorize": "Speichern",
+      "saveCategorizePay": "Speichern & als bezahlt markieren",
       "categorize": "Kategorisieren",
       "view": "Ansehen",
       "empty": "Noch keine Dokumente — oben eines erfassen.",
@@ -3532,7 +3533,9 @@
         "declineReason": "Grund",
         "customer": "Kunde",
         "eventId": "Event-ID (optional)",
-        "markup": "Zuschlag"
+        "markup": "Zuschlag",
+        "reference": "Zahlungsreferenz",
+        "referenceHint": "QR-/ESR-Referenz oder Mitteilung"
       }
     },
     "expenseStatus": {

frontend/src/i18n/locales/en.json

@@ -3502,6 +3502,7 @@
       "categorizedToast": "Document categorized.",
       "triageTitle": "Categorize document",
       "saveCategorize": "Save",
+      "saveCategorizePay": "Save & mark paid",
       "categorize": "Categorize",
       "view": "View",
       "empty": "No documents yet — capture one above.",
@@ -3532,7 +3533,9 @@
         "declineReason": "Reason",
         "customer": "Client",
         "eventId": "Event ID (optional)",
-        "markup": "Markup"
+        "markup": "Markup",
+        "reference": "Payment reference",
+        "referenceHint": "QR / ESR reference or message"
       }
     },
     "expenseStatus": {