Initial implementation of generic Excel-to-DB import tool

Supports .xls and .xlsx, Oracle and PostgreSQL via SQLAlchemy.
Includes CLI (run/inspect/generate-config), YAML config, auto schema
detection, and append/replace/upsert modes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

excel_import/__init__.py

@@ -0,0 +1,4 @@
+from .reader import ExcelReader
+from .importer import Importer
+
+__all__ = ["ExcelReader", "Importer"]