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.

db/models.py

@@ -0,0 +1,32 @@
+"""SQLAlchemy ORM models for users and duties."""
+from sqlalchemy import ForeignKey, Integer, BigInteger, Text
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship
+
+
+class Base(DeclarativeBase):
+    """Declarative base for all models."""
+    pass
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    telegram_user_id: Mapped[int] = mapped_column(BigInteger, unique=True, nullable=False)
+    full_name: Mapped[str] = mapped_column(Text, nullable=False)
+    username: Mapped[str | None] = mapped_column(Text, nullable=True)
+    first_name: Mapped[str | None] = mapped_column(Text, nullable=True)
+    last_name: Mapped[str | None] = mapped_column(Text, nullable=True)
+
+    duties: Mapped[list["Duty"]] = relationship("Duty", back_populates="user")
+
+
+class Duty(Base):
+    __tablename__ = "duties"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    user_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), nullable=False)
+    start_at: Mapped[str] = mapped_column(Text, nullable=False)  # ISO 8601
+    end_at: Mapped[str] = mapped_column(Text, nullable=False)  # ISO 8601
+
+    user: Mapped["User"] = relationship("User", back_populates="duties")