feat(web): 增强任务治理与系统诊断能力

新增任务持久化、筛选分页、取消任务、健康检查与 AI 输入校验，并完善前端历史管理交互与容错重试机制。补充对应单元测试，提升系统稳定性和可运维性。

src/main/resources/static/index.html

@@ -26,7 +26,7 @@
         </header>
 
         <section class="view active" id="view-dashboard" aria-live="polite">
-            <div class="grid cols-3" id="stats-cards">
+            <div class="grid cols-4" id="stats-cards">
                 <article class="card stat">
                     <h3>任务总数</h3>
                     <p id="stat-total">0</p>
@@ -39,8 +39,17 @@
                     <h3>失败任务</h3>
                     <p id="stat-failed">0</p>
                 </article>
+                <article class="card stat">
+                    <h3>系统状态</h3>
+                    <p id="stat-health">-</p>
+                </article>
             </div>
 
+            <article class="card" id="health-card">
+                <h3>健康检查</h3>
+                <p class="muted" id="health-details">加载中...</p>
+            </article>
+
             <div class="grid cols-2">
                 <article class="card">
                     <h3>最近任务</h3>
@@ -94,7 +103,25 @@
         <section class="view" id="view-history">
             <article class="card">
                 <h3>任务列表</h3>
+                <div class="history-toolbar" id="history-toolbar">
+                    <select id="task-filter-status" aria-label="状态筛选">
+                        <option value="">全部状态</option>
+                        <option value="PENDING">PENDING</option>
+                        <option value="RUNNING">RUNNING</option>
+                        <option value="SUCCESS">SUCCESS</option>
+                        <option value="FAILED">FAILED</option>
+                        <option value="CANCELLED">CANCELLED</option>
+                    </select>
+                    <select id="task-filter-type" aria-label="类型筛选">
+                        <option value="">全部类型</option>
+                        <option value="SVN_FETCH">SVN_FETCH</option>
+                        <option value="AI_ANALYZE">AI_ANALYZE</option>
+                    </select>
+                    <input id="task-filter-keyword" placeholder="搜索任务ID/信息" aria-label="关键词搜索">
+                    <button id="btn-task-filter" type="button">查询</button>
+                </div>
                 <div id="task-table" class="table-wrap"></div>
+                <div class="pager" id="task-pager"></div>
             </article>
             <article class="card">
                 <h3>输出文件</h3>