feat: MySQL 索引长度兼容 + 启动自动补列 + 未发布徽标与查询加载态

后端:
- 索引/唯一键改用 mysql_length 前缀索引，适配 MySQL 767 字节限制（error 1071）：knowledge_notes、knowledge_entities、knowledge_graph_blacklist、agent_skills、feedback
- engine.py 新增 _ensure_orm_columns_sync：启动时对比 ORM 元数据，自动 ALTER TABLE 补齐缺失的可空/带默认值列及其索引
- 新增 scripts/audit_index_key_lengths.py 审计全部索引键长度
- 更新 backend/CLAUDE.md 迁移说明

前端:
- 智能体卡片/技能列表：所有者与管理员可见未发布徽标
- 智能体广场：服务端查询进行中时灰显旧结果并悬浮加载提示
- 排行榜入口从 Header 移到欢迎语旁
- threads/hooks.ts：抽取 updateCachedThreadLists 统一处理数组与分页两种缓存形态

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

offline-backend-20260512/backend/scripts/audit_index_key_lengths.py

@@ -0,0 +1,71 @@
+"""Audit ORM index/unique-key byte sizes against MySQL InnoDB prefix limits.
+
+MySQL with the legacy 767-byte InnoDB index-prefix limit (5.6, or 5.7 with
+COMPACT row format) rejects any index whose key exceeds 767 bytes — and
+utf8mb4 costs 4 bytes per char, so an indexed VARCHAR key may total at most
+191 chars. Modern servers (DYNAMIC row format) allow 3072 bytes = 768 chars.
+
+Run: PYTHONPATH=. .venv/Scripts/python scripts/audit_index_key_lengths.py
+"""
+
+from __future__ import annotations
+
+import sys
+
+from sqlalchemy import String, UniqueConstraint
+
+import deerflow.persistence.models  # noqa: F401  (registers all ORM models)
+from deerflow.persistence.base import Base
+
+LIMIT_OLD = 767
+LIMIT_NEW = 3072
+BYTES_PER_CHAR = 4  # utf8mb4
+
+
+def _col_key_bytes(col) -> int | None:
+    t = col.type
+    # unwrap TypeDecorator
+    impl = getattr(t, "impl", None)
+    if impl is not None:
+        t = impl
+    if isinstance(t, String):
+        return (t.length or 255) * BYTES_PER_CHAR
+    return 8  # ints/datetimes/floats — small fixed size, close enough
+
+
+def _key_bytes(col, mysql_length) -> int:
+    full = _col_key_bytes(col) or 0
+    if mysql_length is None:
+        return full
+    if isinstance(mysql_length, dict):
+        prefix = mysql_length.get(col.name)
+    else:
+        prefix = mysql_length
+    if prefix is None:
+        return full
+    return min(full, int(prefix) * BYTES_PER_CHAR)
+
+
+def main() -> int:
+    bad = 0
+    for table in Base.metadata.sorted_tables:
+        keys: list[tuple[str, str, list, object]] = []
+        for idx in table.indexes:
+            keys.append(("INDEX", idx.name, list(idx.columns), idx.dialect_options["mysql"].get("length")))
+        for cons in table.constraints:
+            if isinstance(cons, UniqueConstraint):
+                keys.append(("UNIQUE", cons.name or "?", list(cons.columns), None))
+        for kind, name, cols, mysql_length in keys:
+            total = sum(_key_bytes(c, mysql_length) for c in cols)
+            if total > LIMIT_OLD:
+                bad += 1
+                tag = "EXCEEDS 3072 (fails on ALL MySQL)" if total > LIMIT_NEW else "exceeds 767 (fails on legacy MySQL)"
+                detail = ", ".join(f"{c.name}({getattr(getattr(c.type, 'impl', c.type), 'length', '?')})" for c in cols)
+                print(f"{table.name}: {kind} {name} = {total} bytes [{detail}] -- {tag}")
+    if not bad:
+        print("OK: every index key fits within 767 bytes (utf8mb4 worst case)")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())