fix: 修復 Excel 批次查詢的表名驗證支援 schema.table 格式

原本的正則表達式不支援帶 schema 前綴的表名（如 DWH.DW_MES_LOTMATERIALSHISTORY），
導致查詢失敗並顯示「無效的資料表名稱」錯誤。

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/mes_dashboard/services/excel_query_service.py

@@ -9,9 +9,9 @@ import re
 from datetime import datetime
 from typing import Any, Dict, List, Tuple
 
-import pandas as pd
-
-from mes_dashboard.core.database import get_db_connection
+import pandas as pd
+
+from mes_dashboard.core.database import get_db_connection
 
 
 # Oracle IN clause limit
@@ -77,8 +77,8 @@ def sanitize_column_name(name: str) -> str:
 
 
 def validate_table_name(table_name: str) -> bool:
-    """Validate table name format."""
-    return bool(re.match(r'^[A-Za-z_][A-Za-z0-9_]*$', table_name))
+    """Validate table name format (supports schema.table format)."""
+    return bool(re.match(r'^[A-Za-z_][A-Za-z0-9_]*(\.[A-Za-z_][A-Za-z0-9_]*)?$', table_name))
 
 
 def execute_batch_query(