feat(phase-18): add in-app notification system (T-128, T-129)

backend/alembic/versions/b006_add_notifications_table.py

@@ -0,0 +1,46 @@
+"""add_notifications_table
+
+Revision ID: b006notifications
+Revises: b005v2indexes
+Create Date: 2026-02-09 11:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import UUID
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'b006notifications'
+down_revision: Union[str, Sequence[str], None] = 'b005v2indexes'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Create notifications table."""
+    op.create_table(
+        'notifications',
+        sa.Column('id', UUID(as_uuid=True), primary_key=True, server_default=sa.text('gen_random_uuid()')),
+        sa.Column('user_id', UUID(as_uuid=True), sa.ForeignKey('users.id'), nullable=False),
+        sa.Column('type', sa.String(), nullable=False),
+        sa.Column('title', sa.String(), nullable=False),
+        sa.Column('message', sa.Text(), nullable=True),
+        sa.Column('entity_type', sa.String(), nullable=True),
+        sa.Column('entity_id', UUID(as_uuid=True), nullable=True),
+        sa.Column('read', sa.Boolean(), server_default='false'),
+        sa.Column('created_at', sa.DateTime(), server_default=sa.func.now()),
+    )
+    op.create_index('ix_notifications_user_id', 'notifications', ['user_id'])
+    op.create_index('ix_notifications_read', 'notifications', ['read'])
+    op.create_index('ix_notifications_created_at', 'notifications', ['created_at'])
+
+
+def downgrade() -> None:
+    """Drop notifications table."""
+    op.drop_index('ix_notifications_created_at', table_name='notifications')
+    op.drop_index('ix_notifications_read', table_name='notifications')
+    op.drop_index('ix_notifications_user_id', table_name='notifications')
+    op.drop_table('notifications')