fix(migrations): 合并 alembic 多头(skill_name_zh 与 chain-stages 分支)

20260609_01(skills.name_zh)直接挂在 20260608_01 之下,与
20260608_02..06(chain-stages/parallel-agent 分支)形成两个 head,导致
`alembic upgrade head` 报 Multiple head revisions。新增空 merge 版本
20260609_02 同时指向 20260608_06 与 20260609_01,使 head 归一。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

offline-backend-20260512/backend/packages/harness/deerflow/persistence/migrations/versions/20260609_02_merge_skill_name_zh_and_chain_heads.py

@@ -0,0 +1,30 @@
+"""Merge the skill_name_zh and chain-stages migration heads.
+
+Two lineages both descend from ``20260608_01`` (admin_leaderboard_daily_stats):
+``20260608_02`` … ``20260608_06`` (the chain-stages / parallel-agent branch) and
+``20260609_01`` (skills.name_zh), which branched directly off ``20260608_01``
+instead of off the latest head. That left the graph with two heads and made
+``alembic upgrade head`` fail with "Multiple head revisions are present". This
+no-op merge revision joins both lineages so ``upgrade head`` resolves to a single
+head again.
+
+Revision ID: 20260609_02
+Revises: 20260608_06, 20260609_01
+Create Date: 2026-06-10
+"""
+
+from __future__ import annotations
+
+
+revision = "20260609_02"
+down_revision = ("20260608_06", "20260609_01")
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    pass
+
+
+def downgrade() -> None:
+    pass