db: add digest opt-in/tone on users, email_sends audit table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

alembic/versions/0017_email_digest.py

@@ -0,0 +1,59 @@
+"""email digests: User.email_digest_opt_in, User.digest_tone, email_sends table.
+
+Revision ID: 0017
+Revises: 0016
+Create Date: 2026-05-25
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+
+revision: str = "0017"
+down_revision: Union[str, None] = "0016"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "users",
+        sa.Column(
+            "email_digest_opt_in", sa.Boolean(), nullable=False,
+            server_default=sa.text("1"),
+        ),
+    )
+    op.add_column(
+        "users",
+        sa.Column("digest_tone", sa.String(length=16), nullable=True),
+    )
+
+    op.create_table(
+        "email_sends",
+        sa.Column("id", sa.BigInteger(), autoincrement=True, primary_key=True),
+        sa.Column("user_id", sa.Integer(), nullable=False),
+        sa.Column("kind", sa.String(length=16), nullable=False),
+        sa.Column("sent_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("status", sa.String(length=16), nullable=False),
+        sa.Column("error", sa.String(length=255), nullable=True),
+        sa.ForeignKeyConstraint(
+            ["user_id"], ["users.id"], ondelete="CASCADE",
+        ),
+    )
+    op.create_index(
+        "ix_email_sends_user_kind_sent",
+        "email_sends",
+        ["user_id", "kind", "sent_at"],
+    )
+    op.create_index(
+        op.f("ix_email_sends_user_id"), "email_sends", ["user_id"],
+    )
+
+
+def downgrade() -> None:
+    op.drop_index(op.f("ix_email_sends_user_id"), table_name="email_sends")
+    op.drop_index("ix_email_sends_user_kind_sent", table_name="email_sends")
+    op.drop_table("email_sends")
+    op.drop_column("users", "digest_tone")
+    op.drop_column("users", "email_digest_opt_in")