工作台重命名：无界·无界 → 学会·无界

- ALL_TENANTS / session / seed / migrations 全部同步
- 新增 migrate_rename_tenant() 数据迁移，启动自动 UPDATE 所有表
- migrations/ 模式重构（参考 SalesManager）

backend/migrations/columns.py

@@ -0,0 +1,61 @@
+"""migrations/columns.py — 加列迁移（老表补字段，幂等）"""
+
+
+def _add_column_if_missing(conn, table, column, ddl):
+    """检查列是否存在，不存在才加（幂等）"""
+    from flask_app import _exec, mysql, logger
+
+    cur = conn.cursor(dictionary=True)
+    cur.execute(f"SHOW COLUMNS FROM {table} LIKE %s", (column,))
+    exists = cur.fetchone()
+    cur.close()
+    if not exists:
+        try:
+            _exec(conn, ddl)
+            print(f"[migrate] {table}.{column} 列已添加")
+        except mysql.connector.Error as e:
+            logger.debug(f"add column {table}.{column} skipped: {e}")
+
+
+def migrate_add_columns():
+    """为老表补齐后续新增的字段"""
+    from flask_app import db
+
+    conn = db()
+    try:
+        # tenant 字段（多工作台支持）
+        for table in ["sales_leads", "follow_up_records", "business_proposals",
+                       "operation_projects", "product_versions", "finance_records",
+                       "project_tasks"]:
+            _add_column_if_missing(conn, table, "tenant",
+                f"ALTER TABLE {table} ADD COLUMN tenant VARCHAR(100) NOT NULL DEFAULT '科普·无界'")
+
+        # business_proposals 扩展字段
+        _add_column_if_missing(conn, "business_proposals", "proposal_type",
+            "ALTER TABLE business_proposals ADD COLUMN proposal_type VARCHAR(100) NOT NULL DEFAULT '业务方案'")
+        _add_column_if_missing(conn, "business_proposals", "notes",
+            "ALTER TABLE business_proposals ADD COLUMN notes VARCHAR(2000) NOT NULL DEFAULT ''")
+
+        # product_versions 扩展字段
+        _add_column_if_missing(conn, "product_versions", "platform",
+            "ALTER TABLE product_versions ADD COLUMN platform VARCHAR(100) NOT NULL DEFAULT ''")
+
+        # project_tasks 扩展字段
+        _add_column_if_missing(conn, "project_tasks", "status",
+            "ALTER TABLE project_tasks ADD COLUMN status VARCHAR(50) NOT NULL DEFAULT '未开始'")
+        _add_column_if_missing(conn, "project_tasks", "sort_order",
+            "ALTER TABLE project_tasks ADD COLUMN sort_order INT NOT NULL DEFAULT 0")
+        _add_column_if_missing(conn, "project_tasks", "priority",
+            "ALTER TABLE project_tasks ADD COLUMN priority VARCHAR(10) NOT NULL DEFAULT 'P2'")
+
+        # project_finances 12 个月度预算字段（确收/毛利/回款/费用）
+        for m in ["01","02","03","04","05","06","07","08","09","10","11","12"]:
+            for field in ["rev", "gross", "payment", "cost"]:
+                col = f"{field}_2026_{m}"
+                _add_column_if_missing(conn, "project_finances", col,
+                    f"ALTER TABLE project_finances ADD COLUMN {col} DOUBLE NOT NULL DEFAULT 0")
+
+        conn.commit()
+        print("[migrate] 加列迁移完成")
+    finally:
+        conn.close()