feat(HEL-560): 数据中枢接管数据源/模型池/会员，注册改一次性邀请码

主站
- 新增 m0006 invite_codes 迁移；注册强制邀请码（首个管理员除外），消码与建号
  同一事务，并发提交只有一个能成功
- 新增 /api/hub-admin/* 服务端点（共享 HUB_ADMIN_TOKEN，先于鉴权校验），供数据
  中枢桥接读写会话/密码/模型池/会员/邀请码，并提供供应商模型列表拉取
- 前端：注册表单加邀请码（桌面 login、index.html、移动端）；「系统管理」改为
  「数据中枢」入口指向 8766，原模型池与会员管理分区移除，仅留「行情管理」；
  随之清理陈旧 CSS

数据中枢
- 取消独立账号：删除 hub_admin/hub_sessions 与登录、改密、锁定逻辑，改为校验
  主站 xiaobai_session，仅管理员可进，CSRF 由会话派生，危险操作二次确认走主站
- 控制台新增数据源凭证可编辑区（原有内容一项不删）、供应商制模型池（自动拉取
  /models，失败退回卡内手动录入）、会员管理与邀请码页
- 日夜双主题：颜色收敛为同名 token 换值，SVG 改用 inline style 以吃到变量

自测
- 主站 verify_baseline 通过（498 项）；数据中枢 235 项通过
- tools/verify_datahub_console.py 端到端跑通两服务真实对话；
  tools/verify_datahub_console_ui.py 浏览器跑通门禁/凭证/模型池/会员/主题/1030 窄屏

Co-authored-by: multica-agent <github@multica.ai>

backend/features/accounts/repository.py

@@ -5,6 +5,9 @@ from datetime import datetime, timezone
 from typing import Any
 
 
+INVITE_CONSUMED_MESSAGE = "邀请码无效或已被使用，请联系管理员重新获取。"
+
+
 class AccountRepositoryMixin:
     """Original SQLite account persistence methods, moved without query changes."""
 
@@ -23,11 +26,14 @@ class AccountRepositoryMixin:
         username: str,
         password_salt: str,
         password_hash: str,
+        invite_code: str = "",
     ) -> dict[str, Any]:
         now = datetime.now(timezone.utc).isoformat(timespec="seconds")
         try:
             with self.connect() as connection:
                 role = "admin" if int(connection.execute("SELECT COUNT(*) FROM users").fetchone()[0]) == 0 else "user"
+                if invite_code and not self._consume_invite_code(connection, invite_code, now):
+                    raise ValueError(INVITE_CONSUMED_MESSAGE)
                 cursor = connection.execute(
                     """
                     INSERT INTO users
@@ -37,10 +43,91 @@ class AccountRepositoryMixin:
                     (username, password_salt, password_hash, role, now, now),
                 )
                 user_id = int(cursor.lastrowid)
+                if invite_code:
+                    connection.execute(
+                        "UPDATE invite_codes SET used_by = ? WHERE code = ?",
+                        (user_id, invite_code),
+                    )
         except sqlite3.IntegrityError as exc:
             raise ValueError("该账号名已被使用。") from exc
         return {"id": user_id, "username": username, "role": role, "created_at": now}
 
+    @staticmethod
+    def _consume_invite_code(
+        connection: sqlite3.Connection, code: str, used_at: str
+    ) -> bool:
+        cursor = connection.execute(
+            """
+            UPDATE invite_codes SET status = 'used', used_at = ?
+            WHERE code = ? AND status = 'unused'
+            """,
+            (used_at, code),
+        )
+        return cursor.rowcount > 0
+
+    def invite_code(self, code: str) -> dict[str, Any] | None:
+        with self.connect() as connection:
+            row = connection.execute(
+                """
+                SELECT code, status, note, created_at, used_at, revoked_at, used_by
+                FROM invite_codes WHERE code = ?
+                """,
+                (code,),
+            ).fetchone()
+        return dict(row) if row else None
+
+    def create_invite_codes(
+        self, codes: list[str], note: str, created_by: int
+    ) -> list[str]:
+        now = datetime.now(timezone.utc).isoformat(timespec="seconds")
+        with self.connect() as connection:
+            for code in codes:
+                connection.execute(
+                    """
+                    INSERT INTO invite_codes (code, status, note, created_by, created_at)
+                    VALUES (?, 'unused', ?, ?, ?)
+                    """,
+                    (code, note, created_by or None, now),
+                )
+        return list(codes)
+
+    def revoke_invite_code(self, code: str) -> bool:
+        now = datetime.now(timezone.utc).isoformat(timespec="seconds")
+        with self.connect() as connection:
+            cursor = connection.execute(
+                """
+                UPDATE invite_codes SET status = 'revoked', revoked_at = ?
+                WHERE code = ? AND status = 'unused'
+                """,
+                (now, code),
+            )
+        return cursor.rowcount > 0
+
+    def list_invite_codes(self, limit: int = 100) -> list[dict[str, Any]]:
+        with self.connect() as connection:
+            rows = connection.execute(
+                """
+                SELECT c.code, c.status, c.note, c.created_at, c.used_at, c.revoked_at,
+                       u.username AS used_by_username
+                FROM invite_codes AS c
+                LEFT JOIN users AS u ON u.id = c.used_by
+                ORDER BY c.created_at DESC, c.code
+                LIMIT ?
+                """,
+                (max(1, min(500, int(limit))),),
+            ).fetchall()
+        return [dict(row) for row in rows]
+
+    def count_invite_codes(self) -> dict[str, int]:
+        with self.connect() as connection:
+            rows = connection.execute(
+                "SELECT status, COUNT(*) AS total FROM invite_codes GROUP BY status"
+            ).fetchall()
+        counts = {"unused": 0, "used": 0, "revoked": 0}
+        for row in rows:
+            counts[str(row["status"])] = int(row["total"])
+        return counts
+
     def user_by_username(self, username: str) -> dict[str, Any] | None:
         with self.connect() as connection:
             row = connection.execute(