Initial Claude implementation

app/models/permission.py

@@ -0,0 +1,19 @@
+from sqlalchemy import String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+from app.models.associations import role_permissions
+
+
+class Permission(Base):
+    __tablename__ = "permissions"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    # Convention: "<resource>:<action>", e.g. "users:read".
+    name: Mapped[str] = mapped_column(String(128), unique=True, index=True)
+    description: Mapped[str | None] = mapped_column(String(255), default=None)
+
+    roles: Mapped[list["Role"]] = relationship(  # noqa: F821
+        secondary=role_permissions,
+        back_populates="permissions",
+    )