Enhance XLS upload functionality and update requirements. Added Flask, Flask-SQLAlchemy, and Alembic to requirements. Modified database schema in upload_xls.py for improved data handling and added SQLAlchemy configuration in config.py.

salary_analytics/app/__init__.py

@@ -0,0 +1,17 @@
+from flask import Flask
+import os
+from .extensions import db, migrate
+
+def create_app():
+    app = Flask(__name__)
+    app.config.from_object('salary_analytics.config')
+
+    # Initialize extensions
+    db.init_app(app)
+    migrate.init_app(app, db)
+
+    # Register blueprints or CLI commands here if needed
+    from . import commands
+    app.cli.add_command(commands.upload_xls_cli)
+
+    return app