feat: 项目流水拆分为确收与回款+费用明细两Tab + 数据迁移

后端:
- 新增 expense_data TEXT 列(columns.py迁移)
- 新增 data_split 迁移:旧 budget_data cost/paid → expense_data(幂等)
- sum_budget cost/paid → sum_expense cost/paid(routes.py/helpers.py)
- TABLES 配置加入 expense_data

前端:
- 项目详情弹窗Tab:基本信息→确收与回款→费用明细→执行信息→任务管理→活动
- 确收与回款Tab:月份/确收/毛利/回款/备注
- 费用明细Tab:月份/费用类型/应付/已付/备注
- 项目表格三视图(月/季/总)cost/paid来源切换为expense_data
- 保存逻辑分两路: budget_data(rev/gross/payment)+expense_data(cost/paid)

backend/helpers.py

@@ -63,10 +63,11 @@ def attach_common(conn, resource, items):
 def monthly_finance(conn, tenant="科普·无界"):
     months = [f"2026-{m:02d}" for m in range(1, 13)]
     pfs = rows(conn,
-        "SELECT sign_amount, sign_month, status, budget_data FROM project_finances WHERE tenant=? AND status='已签约'",
+        "SELECT sign_amount, sign_month, status, budget_data, expense_data FROM project_finances WHERE tenant=? AND status='已签约'",
         [tenant])
 
     parsed_budgets = []
+    expense_maps = {}
     for pf in pfs:
         try:
             budget = json.loads(pf.get("budget_data") or "[]")
@@ -79,11 +80,23 @@ def monthly_finance(conn, tenant="科普·无界"):
                 "rev": float(b.get("rev") or 0),
                 "gross": float(b.get("gross") or 0),
                 "payment": float(b.get("payment") or 0),
-                "cost": float(b.get("cost") or 0),
-                "paid": float(b.get("paid") or 0),
             }
         parsed_budgets.append((pf, budget_map))
 
+        # Parse expense_data for cost/paid
+        try:
+            ed = json.loads(pf.get("expense_data") or "[]")
+        except (json.JSONDecodeError, TypeError):
+            ed = []
+        em = {}
+        for e in ed:
+            key = (e.get("month") or "").replace("-", "_")
+            em[key] = {
+                "cost": float(e.get("cost") or 0),
+                "paid": float(e.get("paid") or 0),
+            }
+        expense_maps[pf.get("id", id(pf))] = em
+
     data = []
     for month in months:
         key = month.replace("-", "_")
@@ -96,8 +109,11 @@ def monthly_finance(conn, tenant="科普·无界"):
                 revenue += b["rev"]
                 gross += b["gross"]
                 payment += b["payment"]
-                cost += b["cost"]
-                paid += b["paid"]
+            em = expense_maps.get(pf.get("id", id(pf)), {})
+            e = em.get(key)
+            if e:
+                cost += e["cost"]
+                paid += e["paid"]
         data.append({
             "month": month,
             "revenue": round(revenue, 2),