feat: add migration 0 for initial schema setup

surfsense_backend/alembic/versions/0_initial_schema.py

@@ -0,0 +1,54 @@
+"""Initial schema setup
+
+Revision ID: 0
+Revises: None
+
+Creates all tables from SQLAlchemy models. Idempotent - safe to run on existing databases.
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+
+from alembic import op
+
+revision: str = "0"
+down_revision: str | None = None
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    from app.db import Base
+
+    connection = op.get_bind()
+
+    # Create tables
+    op.execute(sa.text("CREATE EXTENSION IF NOT EXISTS vector"))
+    Base.metadata.create_all(bind=connection)
+
+    # Set up indexes
+    op.execute(
+        sa.text(
+            "CREATE INDEX IF NOT EXISTS document_vector_index ON documents USING hnsw (embedding public.vector_cosine_ops)"
+        )
+    )
+    op.execute(
+        sa.text(
+            "CREATE INDEX IF NOT EXISTS document_search_index ON documents USING gin (to_tsvector('english', content))"
+        )
+    )
+    op.execute(
+        sa.text(
+            "CREATE INDEX IF NOT EXISTS chucks_vector_index ON chunks USING hnsw (embedding public.vector_cosine_ops)"
+        )
+    )
+    op.execute(
+        sa.text(
+            "CREATE INDEX IF NOT EXISTS chucks_search_index ON chunks USING gin (to_tsvector('english', content))"
+        )
+    )
+
+
+def downgrade() -> None:
+    pass