feat: 引入 status_snapshot 统一 provider key 状态管理

- 新增 StatusSnapshot 模型，聚合 OAuth / 账号 / 配额三维状态
- 新增 StatusSnapshotStore 负责快照的持久化与查询
- 重构 response_builder / endpoint_models，基于 snapshot 输出状态字段
- 前端抽取 providerKeyStatus / oauthRefreshFeedback 工具函数，
  统一 PoolManagement、ProviderDetailDrawer、BatchDialog 的状态展示
- errorParser 增加已知 OAuth 错误的友好提示
- refresher 适配 snapshot 写入，account_state 扩展状态分类
- 新增 alembic 迁移及存量数据回填脚本
- 补充前后端单元测试

scripts/backfill_provider_key_status_snapshot.py

@@ -0,0 +1,101 @@
+from __future__ import annotations
+
+import argparse
+from typing import Any
+
+from sqlalchemy import select
+from sqlalchemy.orm import joinedload, load_only
+
+from src.database import create_session
+from src.models.database import Provider, ProviderAPIKey
+from src.services.provider_keys.status_snapshot_store import sync_provider_key_status_snapshot
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Backfill provider_api_keys.status_snapshot from existing OAuth/account/quota fields."
+    )
+    parser.add_argument(
+        "--batch-size",
+        type=int,
+        default=200,
+        help="Number of provider keys to process per commit.",
+    )
+    parser.add_argument(
+        "--include-existing",
+        action="store_true",
+        help="Recompute rows that already have status_snapshot instead of only filling missing rows.",
+    )
+    return parser.parse_args()
+
+
+def build_batch_stmt(
+    *,
+    batch_size: int,
+    last_id: str | None,
+    include_existing: bool,
+) -> Any:
+    stmt = (
+        select(ProviderAPIKey)
+        .options(joinedload(ProviderAPIKey.provider).load_only(Provider.provider_type))
+        .order_by(ProviderAPIKey.id)
+        .limit(batch_size)
+    )
+    if last_id is not None:
+        stmt = stmt.where(ProviderAPIKey.id > last_id)
+    if not include_existing:
+        stmt = stmt.where(ProviderAPIKey.status_snapshot.is_(None))
+    return stmt
+
+
+def main() -> int:
+    args = parse_args()
+    batch_size = max(1, int(args.batch_size or 200))
+    include_existing = bool(args.include_existing)
+
+    db = create_session()
+    processed = 0
+    updated = 0
+    last_id: str | None = None
+
+    try:
+        while True:
+            batch = (
+                db.execute(
+                    build_batch_stmt(
+                        batch_size=batch_size,
+                        last_id=last_id,
+                        include_existing=include_existing,
+                    )
+                )
+                .scalars()
+                .all()
+            )
+            if not batch:
+                break
+
+            for key in batch:
+                last_id = str(key.id)
+                processed += 1
+                previous = getattr(key, "status_snapshot", None)
+                current = sync_provider_key_status_snapshot(key)
+                if current != previous:
+                    updated += 1
+
+            db.commit()
+            print(
+                f"processed={processed} updated={updated} last_id={last_id}",
+                flush=True,
+            )
+
+        print(
+            f"backfill finished: processed={processed} updated={updated} include_existing={include_existing}",
+            flush=True,
+        )
+        return 0
+    finally:
+        db.close()
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())