refactor: 项目模块重构 — 统一渲染 + 配置驱动 + 交互优化

核心重构:
- 提取 renderView() / tdRow() 统一函数，消除三视图 16000+ 字符重复代码
- METRIC_CARDS 配置驱动，调整卡片顺序/单位只需改配置
- 筛选区统一为下拉框（视图 + 状态 + 日期），删除筛选：前缀
- 日历选择器移至顶部工具栏，卡片内不再重复

功能优化:
- 项目状态简化为已签约/待签约
- 新增签约项目总数卡片（月度/季度按签约月份过滤）
- 签约金额/已确收/已回款/应付/已付改为万元单位
- 项目名称固定300px + 省略号 + title悬停
- body min-width 1400px + overflow-x:auto
- 首页费用金额→应付金额

代码清理:
- 删除 monthOpts/quarterOpts/qLabels 等死代码
- 删除 purchase.js（采购→费用模块已另表迁移）
- 财务→项目（侧边栏），采购→费用（全域重命名）

backend/migrations/tables.py

@@ -147,7 +147,7 @@ def migrate_create_tables():
   created_at VARCHAR(30) NOT NULL DEFAULT '',
   updated_at VARCHAR(30) NOT NULL DEFAULT ''
 )""",
-            """CREATE TABLE IF NOT EXISTS purchase_records (
+            """CREATE TABLE IF NOT EXISTS expense_records (
   id INT AUTO_INCREMENT PRIMARY KEY,
   tenant VARCHAR(100) NOT NULL DEFAULT '科普·无界',
   project_name VARCHAR(200) NOT NULL DEFAULT '',

backend/routes.py

@@ -24,7 +24,7 @@ TABLES = {
     "finance": ("finance_records", ["month", "project_name", "record_type", "category", "amount", "occurred_date", "notes", "tenant"]),
     "tasks": ("project_tasks", ["project_id", "phase", "milestone", "task", "owner", "due_date", "blockers", "notes", "status", "sort_order", "priority", "tenant"]),
     "projectFinances": ("project_finances", ["project_id", "tenant", "business_type", "customer_name", "sign_amount", "sign_month", "status", "sales_person", "owner", "total_rev", "total_gross", "total_payment", "total_cost", "total_paid", "budget_data", "start_date", "end_date", "task_type", "task_count", "service_fee_standard", "project_manager", "task_data", "project_code", "contact_name", "contact_phone", "other_info"]),
-    "purchase": ("purchase_records", ["project_name", "purchase_item", "supplier", "amount", "purchase_date", "status", "category", "notes", "tenant"]),
+    "expense": ("expense_records", ["project_name", "purchase_item", "supplier", "amount", "purchase_date", "status", "category", "notes", "tenant"]),
 }
 
 # ---------- 鉴权装饰器 ----------
@@ -322,7 +322,7 @@ def bootstrap():
                 "recent": sorted(all_recent, key=lambda x: x.get("id", 0), reverse=True)[:8],
                 "risks": [],
             }
-            return jsonify({"summary": summary, "sales": [], "proposals": [], "operations": [], "products": [], "finance": [], "projectFinances": [], "financeMonthly": merged_monthly, "tasks": [], "purchase": [], "tenant": tenant, "tenants": allowed})
+            return jsonify({"summary": summary, "sales": [], "proposals": [], "operations": [], "products": [], "finance": [], "projectFinances": [], "financeMonthly": merged_monthly, "tasks": [], "expense": [], "tenant": tenant, "tenants": allowed})
 
         def q(sql, *args):
             return rows(conn, sql, args)
@@ -333,7 +333,7 @@ def bootstrap():
         finance = q("SELECT * FROM finance_records WHERE tenant=? ORDER BY month DESC, id DESC", tenant)
         tasks = q("SELECT * FROM project_tasks WHERE tenant=? ORDER BY phase, sort_order, id", tenant)
         pfs = q("SELECT * FROM project_finances WHERE tenant=? ORDER BY id DESC", tenant)
-        purchase = q("SELECT * FROM purchase_records WHERE tenant=? ORDER BY id DESC", tenant)
+        expense = q("SELECT * FROM expense_records WHERE tenant=? ORDER BY id DESC", tenant)
         signed_pfs = [x for x in pfs if x["status"] == "已签约"]
 
         def parse_budget(pf):
@@ -436,7 +436,7 @@ def bootstrap():
             "recent": q("SELECT * FROM follow_up_records WHERE tenant=? ORDER BY id DESC LIMIT 8", tenant),
             "risks": [{"title": "执行提醒", "content": x["next_action"]} for x in operations if x["next_action"]][:5],
         }
-        return jsonify({"summary": summary, "sales": sales, "proposals": proposals, "operations": operations, "products": products, "finance": finance, "projectFinances": pfs, "financeMonthly": monthly_finance(conn, tenant), "tasks": tasks, "purchase": purchase, "tenant": tenant, "tenants": allowed})
+        return jsonify({"summary": summary, "sales": sales, "proposals": proposals, "operations": operations, "products": products, "finance": finance, "projectFinances": pfs, "financeMonthly": monthly_finance(conn, tenant), "tasks": tasks, "expense": expense, "tenant": tenant, "tenants": allowed})
     finally:
         conn.close()