feat(notifications): per-chat mute settings

- add chat_notification_settings table and migration
- add chat notifications API (get/update muted)
- skip message notifications for muted recipients
- add mute/unmute control in chat info panel

app/chats/models.py

@@ -57,3 +57,19 @@ class ChatMember(Base):
 
     chat: Mapped["Chat"] = relationship(back_populates="members")
     user: Mapped["User"] = relationship(back_populates="memberships")
+
+
+class ChatNotificationSetting(Base):
+    __tablename__ = "chat_notification_settings"
+    __table_args__ = (UniqueConstraint("chat_id", "user_id", name="uq_chat_notification_settings_chat_user"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True, index=True)
+    chat_id: Mapped[int] = mapped_column(ForeignKey("chats.id", ondelete="CASCADE"), nullable=False, index=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
+    muted: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False, server_default="false")
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
+    )