feat: add trusted groups functionality for duty information

- Introduced a new `trusted_groups` table to store groups authorized to receive duty information.
- Implemented functions to add, remove, and check trusted groups in the database.
- Enhanced command handlers to manage trusted groups, including `/trust_group` and `/untrust_group` commands for admin users.
- Updated internationalization messages to support new commands and group status notifications.
- Added unit tests for trusted groups repository functions to ensure correct behavior and data integrity.

duty_teller/db/models.py

@@ -84,3 +84,13 @@ class GroupDutyPin(Base):
 
     chat_id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
     message_id: Mapped[int] = mapped_column(Integer, nullable=False)
+
+
+class TrustedGroup(Base):
+    """Groups authorized to receive duty information."""
+
+    __tablename__ = "trusted_groups"
+
+    chat_id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
+    added_by_user_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
+    added_at: Mapped[str] = mapped_column(Text, nullable=False)