Enhance Telegram bot with database integration and API features

- Added SQLite database support with Alembic for migrations.
- Implemented FastAPI for HTTP API to manage duties.
- Updated configuration to include database URL and HTTP port.
- Created entrypoint script for Docker to handle migrations and permissions.
- Expanded command handlers to register users and display duties.
- Developed a web application for calendar display of duties.
- Included necessary Pydantic schemas and SQLAlchemy models for data handling.
- Updated requirements.txt to include new dependencies for FastAPI and SQLAlchemy.

alembic/env.py

@@ -0,0 +1,50 @@
+"""Alembic env: use config DATABASE_URL and db.models.Base."""
+import os
+import sys
+from logging.config import fileConfig
+
+from dotenv import load_dotenv
+from sqlalchemy import create_engine
+from alembic import context
+
+load_dotenv()
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from db.models import Base
+
+config = context.config
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+database_url = os.getenv("DATABASE_URL", "sqlite:///data/duty_teller.db")
+config.set_main_option("sqlalchemy.url", database_url)
+
+target_metadata = Base.metadata
+
+connect_args = {"check_same_thread": False} if "sqlite" in database_url else {}
+
+
+def run_migrations_offline() -> None:
+    context.configure(
+        url=database_url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    engine = create_engine(database_url, connect_args=connect_args)
+    with engine.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()