feat(douyu): 和平小店扭蛋碎片查询 + 深色模式修复 + 任务状态 WS 即时推送

- 碎片: 新增 query_xpd_fragments 任务, 复用 e语言 gamecoin 接口取扭蛋币 jb2,
  账号已存角色回退(规避 Livelink 风控), accounts.xpd_fragments 字段与迁移
- 列表: 和平小店移除鱼翅/限制兑换/换绑时间列, 新增扭蛋碎片列;
  操作区硬编码白底改用 theme token, 深色模式适配(三个手册共用)
- 轮询: 任务状态经 WS(level=task)即时推送(二维码/绑定进度即时展示),
  pending/running/终态全覆盖, REST/WS 载荷统一 douyu_task_payload,
  raw 快照递归剥离, HTTP 轮询降频 5s/30s 兜底

web/backend/migrations/versions/20260807_0017_douyu_xpd_fragments.py

@@ -0,0 +1,35 @@
+"""斗鱼和平小店账号新增扭蛋碎片字段
+
+Revision ID: 20260807_0017
+Revises: 20260806_0016
+Create Date: 2026-08-07
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = "20260807_0017"
+down_revision: Union[str, None] = "20260806_0016"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    bind = op.get_bind()
+    if not sa.inspect(bind).has_table("accounts"):
+        return
+    columns = {column["name"] for column in sa.inspect(bind).get_columns("accounts")}
+    if "xpd_fragments" not in columns:
+        op.add_column("accounts", sa.Column("xpd_fragments", sa.Integer(), nullable=True))
+
+
+def downgrade() -> None:
+    bind = op.get_bind()
+    if not sa.inspect(bind).has_table("accounts"):
+        return
+    columns = {column["name"] for column in sa.inspect(bind).get_columns("accounts")}
+    if "xpd_fragments" in columns:
+        op.drop_column("accounts", "xpd_fragments")