Add new Mention model

h/models/mention.py

@@ -1,4 +1,5 @@
 import sqlalchemy as sa
+from sqlalchemy.orm import Mapped, mapped_column
 
 from h.db import Base
 from h.db.mixins import Timestamps
@@ -8,17 +9,17 @@
 class Mention(Base, Timestamps):  # pragma: nocover
     __tablename__ = "mention"
 
-    id = sa.Column(sa.Integer, autoincrement=True, primary_key=True)
+    id: Mapped[int] = mapped_column(sa.Integer, autoincrement=True, primary_key=True)
 
-    annotation_id = sa.Column(
+    annotation_id: Mapped[int] = mapped_column(
         sa.Integer,
         sa.ForeignKey("annotation_slim.id", ondelete="CASCADE"),
         nullable=False,
     )
     """FK to annotation_slim.id"""
     annotation = sa.orm.relationship("AnnotationSlim")
 
-    user_id = sa.Column(
+    user_id: Mapped[int] = mapped_column(
         sa.Integer,
         sa.ForeignKey("user.id", ondelete="CASCADE"),
         nullable=False,
@@ -27,5 +28,5 @@ class Mention(Base, Timestamps):  # pragma: nocover
     """FK to user.id"""
     user = sa.orm.relationship("User")
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return helpers.repr_(self, ["id", "annotation_id", "user_id"])