feat(sprint10): Phase 4+5 — Frontend import wizard + integration testing

Phase 4 — Frontend Import Wizard:
- bank-import.ts service: types (BankImportSession, BankTransaction,
  CsvColumnMapping, ImportSessionStatus, MatchStatus) + 12 React Query hooks
  (sessions, transactions, mappings, upload/confirm/skip/assign/complete)
- /finance/import page: 4-step wizard (Upload -> Map -> Review -> Confirm)
  * Drag-and-drop upload with bank format auto-detect (MT940/CAMT.053/CSV)
  * CSV column mapping editor (saves as reusable mapping)
  * Review table with color-coded MATCHED/SUGGESTED/UNMATCHED/CONFIRMED rows,
    confidence % badges, member-assign Combobox, skip/confirm/bulk-confirm
  * Completion summary + import history table with resume action
- de.json + en.json: full bankImport.* namespace (steps, upload, map, review,
  complete, history, status, sessionStatus, actions, errors)
- Navigation: Finanzen converted to nested submenu (Uebersicht + Import)

Phase 5 — Integration Testing:
- docker compose down -v + up -d --build (clean rebuild)
- Playwright e2e/sprint10-system-test.spec.ts: verifies /finance/import
  unauthenticated -> /login?callbackUrl=%2Ffinance%2Fimport (PASS)
- Backend health + frontend route registration verified

Bugfix bundled (blocked backend startup):
- PaymentRepository: countOverdueByClubId* queries referenced non-existent
  Payment.dueDate column (regression from Sprint 9 Phase 6, commit 57f418f).
  Switched to Payment.periodTo (the implicit due date for billing periods).

cannamanage-frontend/messages/en.json

@@ -958,6 +958,117 @@
       "noPayments": "No payments yet"
     }
   },
+  "bankImport": {
+    "title": "Bank Statement Import",
+    "subtitle": "Import bank statements, match transactions to members, and confirm fee payments",
+    "steps": {
+      "upload": "Upload",
+      "map": "Map Columns",
+      "review": "Review",
+      "complete": "Complete"
+    },
+    "upload": {
+      "title": "Upload bank statement",
+      "description": "Supported formats: MT940 (.sta, .mt940, .txt), CAMT.053 (.xml), CSV (.csv)",
+      "dropzone": "Drag a file here or click to select",
+      "selectFile": "Select file",
+      "format": "Format",
+      "mapping": "CSV Template (optional)",
+      "noMapping": "Auto-detect",
+      "upload": "Upload",
+      "uploading": "Uploading…"
+    },
+    "map": {
+      "title": "Map CSV columns",
+      "description": "Specify which columns contain which data",
+      "dateColumn": "Date column",
+      "amountColumn": "Amount column",
+      "referenceColumn": "Reference column",
+      "counterpartyColumn": "Counterparty column",
+      "delimiter": "Delimiter",
+      "dateFormat": "Date format",
+      "saveAsTemplate": "Save as default template",
+      "templateName": "Template name",
+      "continue": "Continue",
+      "saving": "Saving…"
+    },
+    "review": {
+      "title": "Review transactions",
+      "description": "Confirm matches or assign members manually",
+      "matched": "Matched",
+      "suggested": "Suggested",
+      "unmatched": "Unmatched",
+      "skipped": "Skipped",
+      "total": "Total",
+      "progress": "Review progress",
+      "confirmAll": "Confirm all matched",
+      "confirmingAll": "Confirming…",
+      "sortBy": "Sort by",
+      "sortConfidence": "Confidence",
+      "sortAmount": "Amount",
+      "sortDate": "Date",
+      "date": "Date",
+      "amount": "Amount",
+      "counterparty": "Counterparty",
+      "reference": "Reference",
+      "match": "Match",
+      "actions": "Actions",
+      "noTransactions": "No transactions found",
+      "resume": "Resume"
+    },
+    "complete": {
+      "title": "Complete session",
+      "description": "Seal the session — sealed sessions are immutable (GoBD §147 AO)",
+      "summary": "Summary",
+      "confirmed": "Confirmed",
+      "skipped": "Skipped",
+      "open": "Open",
+      "seal": "Seal session",
+      "sealing": "Sealing…",
+      "sealed": "Session sealed",
+      "sealedDescription": "This session is now immutable and audit-proof.",
+      "back": "Back to Finance"
+    },
+    "history": {
+      "title": "Import history",
+      "description": "Previous import sessions",
+      "noSessions": "No imports yet",
+      "filename": "Filename",
+      "uploaded": "Uploaded",
+      "status": "Status",
+      "resume": "Resume"
+    },
+    "status": {
+      "MATCHED": "Matched",
+      "SUGGESTED": "Suggested",
+      "UNMATCHED": "Unmatched",
+      "CONFIRMED": "Confirmed",
+      "SKIPPED": "Skipped"
+    },
+    "sessionStatus": {
+      "PENDING": "Pending",
+      "IN_REVIEW": "In Review",
+      "COMPLETED": "Completed",
+      "FAILED": "Failed",
+      "CANCELLED": "Cancelled"
+    },
+    "actions": {
+      "confirm": "Confirm",
+      "assign": "Assign",
+      "skip": "Skip",
+      "searchMember": "Search member…",
+      "noMembersFound": "No members found",
+      "cancel": "Cancel"
+    },
+    "errors": {
+      "uploadFailed": "Upload failed",
+      "noFile": "Please select a file",
+      "confirmFailed": "Confirm failed",
+      "assignFailed": "Assign failed",
+      "skipFailed": "Skip failed",
+      "completeFailed": "Complete failed"
+    }
+  },
   "documents": {
     "title": "Document Archive",
     "description": "Manage and archive club documents",