feat: add prompt startup actions and shared vision config

backend/migrations/versions/20260801_0009_add_assistant_startup.py

@@ -0,0 +1,32 @@
+"""add assistant startup actions
+
+Revision ID: 20260801_0009
+Revises: 20260717_0008
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = "20260801_0009"
+down_revision: str | Sequence[str] | None = "20260717_0008"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "assistants",
+        sa.Column(
+            "startup",
+            sa.JSON(),
+            server_default=sa.text("'{}'"),
+            nullable=False,
+        ),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("assistants", "startup")