feat: 1-to-1 message render + web data-lake backend

backend/migrations/versions/a9c3e7f1d2b4_media_unique_id.py

@@ -0,0 +1,27 @@
+"""media unique_id for edit detection
+
+Revision ID: a9c3e7f1d2b4
+Revises: f7a2c9e1b3d5
+Create Date: 2026-05-30 04:00:00.000000
+
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "a9c3e7f1d2b4"
+down_revision: str | None = "f7a2c9e1b3d5"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    op.add_column("media", sa.Column("unique_id", sa.String(), nullable=True))
+    op.add_column("media_versions", sa.Column("unique_id", sa.String(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("media_versions", "unique_id")
+    op.drop_column("media", "unique_id")