Initial commit: Flask calorie counter app setup

Add base Flask application with user authentication, SQLAlchemy models for users, units, and food items, admin blueprint, and basic templates. Includes database migration setup, login form, and seed script for initial user creation.

application/__init__.py

@@ -0,0 +1,18 @@
+from flask import Flask
+from flask_login import LoginManager  # type: ignore
+from flask_sqlalchemy import SQLAlchemy
+from flask_migrate import Migrate
+from application.admin.routes import admin_bp
+
+
+app = Flask(__name__)  # Init Flask app
+app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///data.db"
+
+
+db = SQLAlchemy(app=app)  # Init SQLAlchemy
+migrate = Migrate(app=app, db=db)  # Init Migration
+
+login_manager = LoginManager(app=app)  # Init login manager
+
+# Register blueprints
+app.register_blueprint(admin_bp)