fix(alembic): merge v2.6.0 migration heads

Author: zgqgit

src/backend/bisheng/core/database/alembic/versions/v2_6_0_f048_merge_f046_f047_heads.py

@@ -0,0 +1,29 @@
+"""F048: merge the knowledge-file and assistant-knowledge-auth heads.
+
+Revision ID: f048_merge_f046_f047_heads
+Revises: f046_knowledge_file_name_length, f047_assistant_knowledge_auth
+Create Date: 2026-07-17
+
+The two schema changes landed concurrently from ``f045_dks_is_hidden``. This
+no-op revision rejoins both migration branches so deployments can continue to
+use the canonical ``alembic upgrade head`` command.
+"""
+
+from collections.abc import Sequence
+from typing import Union
+
+revision: str = "f048_merge_f046_f047_heads"
+down_revision: Union[str, Sequence[str], None] = (
+    "f046_knowledge_file_name_length",
+    "f047_assistant_knowledge_auth",
+)
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    pass
+
+
+def downgrade() -> None:
+    pass