feat(v1.9.0): Bootstrap 5 迁移第 3/4、4/4 轮（抽屉、表单、大屏内部）

版本号保持 1.9.0，仍为纯前端改动：
- 日历抽屉：快速输入改 form-control，任务/到期列表改 Bootstrap list-group，加急标签改 badge
- 客户详情：套餐下拉、开始日、天数/次数、终止日统一 form-select / form-control
- 大屏内部：KPI 改 card，TOP 榜与今日列表改 list-group，加急改 badge；热力网格保留自绘
- app.css 增加 Bootstrap 收敛规则（list-group 透明背景、任务分隔线）

验证：无头 Chrome 实拍日历、客户详情、大屏三页（shots/bs3-*.png），页面正常渲染
数据库与业务逻辑零改动

internal/web/templates/pages/calendar.html

@@ -83,7 +83,7 @@
           <input type="hidden" name="pkg" value="{{.D.PkgID}}">
           <input type="hidden" name="tag" value="{{.D.Tag}}">
           <input type="hidden" name="back" value="{{.D.Back}}">
-          <input type="text" name="tail" placeholder="输入手机尾号，回车即可完成" maxlength="8" autocomplete="off" inputmode="numeric" aria-label="手机尾号快速完成">
+          <input class="form-control form-control-sm" type="text" name="tail" placeholder="输入手机尾号，回车即可完成" maxlength="8" autocomplete="off" inputmode="numeric" aria-label="手机尾号快速完成">
           <button class="btn btn-sm btn-primary" type="submit">完成</button>
           <button type="button" class="btn btn-sm btn-ghost keypad-toggle" data-keypad-toggle title="切换触控/PC 模式" aria-label="切换触控/PC 模式">⌨</button>
         </form>
@@ -115,7 +115,7 @@
             <input type="hidden" name="back" value="{{.D.Back}}">
             <ul class="pick-list">
               {{range .D.PickRows}}
-              <li>
+              <li class="list-group-item px-0">
                 <label>
                   <input type="checkbox" name="sub_ids" value="{{.ID}}"{{if not .Done}}{{if not .Skipped}} checked{{end}}{{end}}>
                   <span class="ticket" style="--tag:{{.PackageColor}}"><b>{{.CustomerTail}}</b>{{.CustomerName}}</span>
@@ -139,16 +139,16 @@
         {{end}}
 
         {{if .D.Tasks}}
-        <ul class="task-list">
+        <ul class="list-group list-group-flush task-list">
           {{range .D.Tasks}}
           {{if or .Done .Skipped}}
-          <li class="task task-done" style="--asg:{{.AssigneeHex}}">
+          <li class="list-group-item task task-done px-0" style="--asg:{{.AssigneeHex}}">
             <details class="done-fold">
               <summary>
                 <span class="ticket" style="--tag:{{.PackageColor}}"><b>{{.CustomerTail}}</b>{{.CustomerName}}</span>
                 <span class="pkg">{{.PackageName}}</span>
                 <span class="chip {{if .Done}}chip-active{{else}}chip-paused{{end}}">{{if .Done}}已完成{{else}}已跳过{{end}}</span>
-                {{if .Urgent}}<span class="tag-urgent">加急</span>{{end}}
+                {{if .Urgent}}<span class="badge text-bg-danger tag-urgent">加急</span>{{end}}
                 <span class="fold-caret" aria-hidden="true"></span>
               </summary>
               <div class="done-detail">
@@ -181,7 +181,7 @@
             </details>
           </li>
           {{else}}
-          <li class="task{{if .Urgent}} urgent{{end}}" style="--asg:{{.AssigneeHex}}">
+          <li class="list-group-item task{{if .Urgent}} urgent{{end}} px-0" style="--asg:{{.AssigneeHex}}">
             <div class="task-main">
               <a class="task-title" href="/customers/{{.CustomerID}}">
                 <span class="ticket" style="--tag:{{.PackageColor}}"><b>{{.CustomerTail}}</b>{{.CustomerName}}</span>
@@ -234,7 +234,7 @@
       <section class="drawer-block">
         <h3>这天到期 <em>{{len .D.Due}}</em></h3>
         {{if .D.Due}}
-        <ul class="due-list">
+        <ul class="list-group list-group-flush due-list">
           {{range .D.Due}}
           <li>
             <a class="due-main" href="/customers/{{.CustomerID}}">