Fix multi-account bank reconciliation and output filename

app/modules/bank_statement_analyzer/service.py

@@ -210,6 +210,15 @@ def _claim_jobs() -> list[str]:
         db.close()
 
 
+
+def _workbook_filename(metas) -> str:
+    """Return BankName_ClientName.xlsx using filesystem-safe segments."""
+    banks = sorted({_segment(getattr(meta, "bank_name", ""), "Bank") for meta in metas if str(getattr(meta, "bank_name", "") or "").strip()})
+    customers = sorted({_segment(getattr(meta, "customer_name", ""), "Client") for meta in metas if str(getattr(meta, "customer_name", "") or "").strip()})
+    bank_label = banks[0] if len(banks) == 1 else ("Multi_Bank" if banks else "Bank")
+    client_label = customers[0] if len(customers) == 1 else ("Multiple_Clients" if customers else "Client")
+    return f"{bank_label}_{client_label}.xlsx"
+
 def _process_job(job_id: str) -> None:
     db = CommonSessionLocal()
     try:
@@ -229,7 +238,7 @@ def _process_job(job_id: str) -> None:
         )
         job.progress_percent = 75
         db.commit()
-        output = output_dir / "Bank_Statement_Analysis.xlsx"
+        output = output_dir / _workbook_filename(metas)
         export_excel(
             output,
             metas,