feat(persistence): add WorkspaceRow ORM model

新建 backend/packages/harness/deerflow/persistence/workspace/{__init__.py, model.py}
+ 在 persistence.models.__init__ 注册 WorkspaceRow 让 Base.metadata.create_all
能自动建表。

WorkspaceRow schema（来自 workspace-schema-design §2.1 锁定版）：
  - id String(36) PK（UUID v4 字符串，与 users.id 对齐）
  - name String(64) NOT NULL（显示名）
  - slug String(32) NOT NULL UNIQUE（URL 标识，正则 ^[a-z0-9](-?[a-z0-9])*$）
  - status String(16) default 'active'（active/suspended/deleted）
  - owner_id String(36) FK users.id ON DELETE RESTRICT（删 owner 时阻拦，
    必须先转让所有权）
  - created_at / updated_at DateTime(tz=True)

每列 + 表都带中文 comment（沿用 commit 9ff79055 的 convention）。

Stage 0 PR3 T3.3。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/packages/harness/deerflow/persistence/models/__init__.py

@@ -8,6 +8,7 @@ The actual ORM classes have moved to entity-specific subpackages:
 - ``deerflow.persistence.run``
 - ``deerflow.persistence.feedback``
 - ``deerflow.persistence.user``
+- ``deerflow.persistence.workspace``  (Stage 0 PR3)
 
 ``RunEventRow`` remains in ``deerflow.persistence.models.run_event`` because
 its storage implementation lives in ``deerflow.runtime.events.store.db`` and
@@ -19,5 +20,6 @@ from deerflow.persistence.models.run_event import RunEventRow
 from deerflow.persistence.run.model import RunRow
 from deerflow.persistence.thread_meta.model import ThreadMetaRow
 from deerflow.persistence.user.model import UserRow
+from deerflow.persistence.workspace.model import WorkspaceRow
 
-__all__ = ["FeedbackRow", "RunEventRow", "RunRow", "ThreadMetaRow", "UserRow"]
+__all__ = ["FeedbackRow", "RunEventRow", "RunRow", "ThreadMetaRow", "UserRow", "WorkspaceRow"]

backend/packages/harness/deerflow/persistence/workspace/__init__.py

@@ -0,0 +1,16 @@
+"""Workspace persistence — ORM model + repository.
+
+A workspace is the multi-tenant scope unit. Every user has at least
+one (auto-created on registration; their personal workspace where
+they are sole owner). Team plans get multi-member workspaces.
+
+Stage 0 PR3 introduces the schema + repository; PR4 wires it into
+the registration / login flow; PR5+ ALTER existing business tables
+to FK back to ``workspaces.id``.
+"""
+
+from __future__ import annotations
+
+from deerflow.persistence.workspace.model import WorkspaceRow
+
+__all__ = ["WorkspaceRow"]

backend/packages/harness/deerflow/persistence/workspace/model.py

@@ -0,0 +1,58 @@
+"""ORM model for workspaces (multi-tenant scope)."""
+
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from sqlalchemy import DateTime, ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from deerflow.persistence.base import Base
+
+
+class WorkspaceRow(Base):
+    __tablename__ = "workspaces"
+
+    id: Mapped[str] = mapped_column(
+        String(36),
+        primary_key=True,
+        comment="工作空间主键，UUID 字符串（36 字符），与 users.id 类型对齐",
+    )
+    name: Mapped[str] = mapped_column(
+        String(64),
+        nullable=False,
+        comment="工作空间显示名（用户注册时默认 <email 前缀>'s Workspace）",
+    )
+    slug: Mapped[str] = mapped_column(
+        String(32),
+        nullable=False,
+        unique=True,
+        comment="URL 标识（^[a-z0-9](-?[a-z0-9])*$，3-32 字符）；全局唯一，DB 存小写",
+    )
+    status: Mapped[str] = mapped_column(
+        String(16),
+        nullable=False,
+        default="active",
+        comment='状态："active"（正常）/ "suspended"（平台 admin 暂停）/ "deleted"（软删）',
+    )
+    owner_id: Mapped[str] = mapped_column(
+        String(36),
+        ForeignKey("users.id", ondelete="RESTRICT"),
+        nullable=False,
+        comment="所有者 user_id；与 workspace_memberships 中 role='owner' 行严格一致（事务保证）；删除 owner 时 RESTRICT 阻拦（必须先转让所有权）",
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(UTC),
+        comment="创建时间（UTC）",
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(UTC),
+        onupdate=lambda: datetime.now(UTC),
+        comment="最近更新时间（UTC，写入时自动更新）",
+    )
+
+    __table_args__ = ({"comment": ("工作空间表（多租户隔离粒度单位）。每个用户注册时自动建一个 1 人 workspace，owner 即注册者。团队订阅时 workspace 可有多个 member。")},)