feat: 删除部门模块 + 任务系统重构 + 布局修复

- 删除部门(Home)侧边栏入口、面板及相关代码
- 删除 home.js，chartOptions 等图表工具迁移到 utils.js
- 清理 render()、togglePhase、filterPhaseTasks 等死代码
- 任务列表改为平铺(取消阶段分组)，支持拖拽排序
- 任务表单加开始时间字段，重组字段布局为三列
- 任务展开面板改为竖排：时间、任务进展、卡点与备注
- 视图按钮和新增任务按钮移入任务卡片顶部
- 修复 index.html div 嵌套不平衡导致布局塌陷
- 修复 savedTab 校验和 switchTenant 侧边栏 active 同步
- 总览工作台只显示预算/发生总览入口
- 性能面板 id 去重

templates/index.html

@@ -63,10 +63,6 @@
         <div class="w-8 h-px bg-slate-700 my-2"></div>
         <!-- 导航 Tab 图标 -->
         <div class="flex flex-col items-center gap-1 w-14" id="sidebarTabs">
-          <div class="sidebar-tab active" data-tab="home" onclick="switchTab('home')" title="部门">
-            <i data-lucide="trending-up" style="width:20px;height:20px"></i>
-            <span class="text-[10px] mt-1">部门</span>
-          </div>
           <div class="sidebar-tab" data-tab="plan" onclick="switchTab('plan')" title="预算">
             <i data-lucide="calendar-range" style="width:20px;height:20px"></i>
             <span class="text-[10px] mt-1">预算</span>
@@ -122,21 +118,19 @@
     </header>
 
     <main class="px-8 py-6">
-      <section id="home" class="panel active"></section>
       <section id="overview_plan" class="panel"></section>
       <section id="overview_finance" class="panel"></section>
       <section id="projects" class="panel"></section>
       <section id="proposals" class="panel"></section>
       <section id="products" class="panel"></section>
       <section id="performance" class="panel"></section>
-      <section id="performance" class="panel"></section>
       <section id="finance" class="panel"></section>
-      <section id="plan" class="panel"></section>
+      <section id="plan" class="panel active"></section>
     </main>
       </div><!-- 关闭主内容区 -->
     </div><!-- 关闭 flex 容器 -->
     <aside id="drawer" class="drawer" aria-hidden="true"></aside>
-    <div id="taskModal" class="task-modal"></div>
+    <div id="taskModal"></div>
     <!-- 新增项目模态框 -->
     <div id="newProjectModal" class="hidden fixed inset-0 z-50 flex items-center justify-center bg-black/40" onclick="closeNewProjectModal()">
       <div class="bg-white rounded-2xl shadow-2xl w-full max-w-md mx-4" onclick="event.stopPropagation()">
@@ -155,7 +149,6 @@
       </div>
     </div>
     <script src="{{ url_for('static', filename='modules/utils.js') }}"></script>
-    <script src="{{ url_for('static', filename='modules/home.js') }}"></script>
     <script src="{{ url_for('static', filename='modules/projects.js') }}"></script>
     <script src="{{ url_for('static', filename='modules/proposals.js') }}"></script>
     <script src="{{ url_for('static', filename='modules/products.js') }}"></script>