fix: address account valuation review findings

dashboard/app.py

@@ -4,6 +4,7 @@ import sys
 from pathlib import Path
 
 import streamlit as st
+from jarca_ledger_mcp.adapters.streamlit import overview_gateway
 
 # Streamlit executes this file as a script, so ensure absolute dashboard imports
 # resolve identically to package imports used by tests.
@@ -38,7 +39,11 @@ def main() -> None:
         return
 
     db_path = get_db_path()
+    db_status = overview_gateway.get_ledger_db_status(db_path=db_path, include_hash=False, include_integrity=False)
     inject_app_css()
+    if not db_status.get("success"):
+        st.error("Ledger DB를 사용할 수 없습니다: " + db_status.get("error", "ledger database is unavailable"))
+        return
     pages = ["월정산", "요약", "자산/마감", "거래내역", "확인필요 큐", "미분류", "분류 규칙", "카테고리", "계좌", "Import"]
     query_page = st.query_params.get("page")
     page = validate_dashboard_page(query_page, pages)