feat: Add Single User authentication to Selfhosted (#870)

* Single user/password for selfhosted

* fix revision id latest migration

server/migrations/versions/e1f093f7f124_add_password_hash_to_user.py

@@ -0,0 +1,25 @@
+"""add password_hash to user table
+
+Revision ID: e1f093f7f124
+Revises: 623af934249a
+Create Date: 2026-02-19 00:00:00.000000
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "e1f093f7f124"
+down_revision: Union[str, None] = "623af934249a"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("user", sa.Column("password_hash", sa.String(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("user", "password_hash")