Forbid deleting admin user via api

Author: r4victor

…6bfd_add_usermodel_original_name_and_.py …d_usermodel_deleted_and_original_name.pysrc/dstack/_internal/server/migrations/versions/cc3912316bfd_add_usermodel_original_name_and_.py renamed to src/dstack/_internal/server/migrations/versions/06e977bc61c7_add_usermodel_deleted_and_original_name.py src/dstack/_internal/server/migrations/versions/cc3912316bfd_add_usermodel_original_name_and_.py renamed to src/dstack/_internal/server/migrations/versions/06e977bc61c7_add_usermodel_deleted_and_original_name.py

@@ -1,36 +1,39 @@
-"""Add UserModel.original_name and ProjectModel.original_name
+"""Add UserModel.deleted and original_name
 
-Revision ID: cc3912316bfd
-Revises: 965760bacf93
-Create Date: 2025-11-26 11:04:18.383458
+Revision ID: 06e977bc61c7
+Revises: 7d1ec2b920ac
+Create Date: 2025-11-26 11:43:34.825686
 
 """
 
 import sqlalchemy as sa
 from alembic import op
 
 # revision identifiers, used by Alembic.
-revision = "cc3912316bfd"
-down_revision = "965760bacf93"
+revision = "06e977bc61c7"
+down_revision = "7d1ec2b920ac"
 branch_labels = None
 depends_on = None
 
 
 def upgrade() -> None:
     # ### commands auto generated by Alembic - please adjust! ###
-    with op.batch_alter_table("projects", schema=None) as batch_op:
-        batch_op.add_column(sa.Column("original_name", sa.String(length=50), nullable=True))
-
     with op.batch_alter_table("users", schema=None) as batch_op:
+        batch_op.add_column(
+            sa.Column("deleted", sa.Boolean(), server_default=sa.text("0"), nullable=False)
+        )
         batch_op.add_column(sa.Column("original_name", sa.String(length=50), nullable=True))
 
+    with op.batch_alter_table("projects", schema=None) as batch_op:
+        batch_op.add_column(sa.Column("original_name", sa.String(length=50), nullable=True))
     # ### end Alembic commands ###
 
 
 def downgrade() -> None:
     # ### commands auto generated by Alembic - please adjust! ###
     with op.batch_alter_table("users", schema=None) as batch_op:
         batch_op.drop_column("original_name")
+        batch_op.drop_column("deleted")
 
     with op.batch_alter_table("projects", schema=None) as batch_op:
         batch_op.drop_column("original_name")

src/dstack/_internal/server/migrations/versions/965760bacf93_add_usermodel_deleted.py

@@ -188,6 +188,9 @@ async def delete_users(
     user: UserModel,
     usernames: List[str],
 ):
+    if _ADMIN_USERNAME in usernames:
+        raise ServerClientError("User 'admin' cannot be deleted")
+
     res = await session.execute(
         select(UserModel)
         .where(