feat(billing): add plan_billing sibling table for Stripe + catalog metadata

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/alembic/versions/f236a91224d0_add_plan_billing.py

@@ -0,0 +1,41 @@
+"""add plan_billing
+
+Revision ID: f236a91224d0
+Revises: 2aa73d3231c2
+Create Date: 2026-05-06 07:30:06.807887
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'f236a91224d0'
+down_revision: Union[str, None] = '2aa73d3231c2'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "plan_billing",
+        sa.Column("plan", sa.String(50), sa.ForeignKey("plan_limits.plan"), primary_key=True),
+        sa.Column("display_name", sa.String(255), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column("monthly_price_cents", sa.Integer(), nullable=True),
+        sa.Column("annual_price_cents", sa.Integer(), nullable=True),
+        sa.Column("stripe_product_id", sa.String(255), nullable=True),
+        sa.Column("stripe_monthly_price_id", sa.String(255), nullable=True),
+        sa.Column("stripe_annual_price_id", sa.String(255), nullable=True),
+        sa.Column("is_public", sa.Boolean(), nullable=False, server_default=sa.text("true")),
+        sa.Column("is_archived", sa.Boolean(), nullable=False, server_default=sa.text("false")),
+        sa.Column("sort_order", sa.Integer(), nullable=False, server_default=sa.text("0")),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("plan_billing")