docs: update project structure and add database documentation

- Add tests/ directory to .gitignore
- Document database connectivity with pyodbc and config
- Add project structure and file organization guidelines
- Update installation steps to use requirements.txt
- Document new dependencies: pandas, openpyxl, pyodbc

config/__init__.py

@@ -0,0 +1 @@
+# Config package

config/database_config.py

@@ -0,0 +1,9 @@
+# ================= SQL Server 配置 =================
+SQL_SERVER_CONFIG = {
+    'driver': 'ODBC Driver 18 for SQL Server',
+    'server': '192.168.110.114',
+    'database': 'CompanyDB',
+    'username': 'peng',
+    'password': 'Cqbld123456.',
+    'TrustServerCertificate': 'yes'
+}