✨ feat(vscode): 看板顶部加筛选框，按标题 / 工单号 / PR 号过滤卡片

工单多了以后靠肉眼在四列里翻太慢。顶部输入框按空白分词逐词 AND 匹配
标题、工单号、PR 号，`#427` 与 `427` 等价，纯数字按包含匹配，记不全
编号也能搜到。筛选只收窄渲染，拖拽与依赖锁定仍按全量列表算；列头角标
在筛选时显示「可见 / 总数」。

vscode/webview-ui/src/components/PanelHeader.tsx

@@ -1,8 +1,11 @@
 import type { ReleaseAction, ReleaseStatus } from '../hooks/useIssues'
-import { GitCommit, ListPlus, Loader2, Lock, RefreshCw, Rocket, Settings, Unlock, User, Users } from 'lucide-react'
+import { GitCommit, ListPlus, Loader2, Lock, RefreshCw, Rocket, Search, Settings, Unlock, User, Users, X } from 'lucide-react'
 import { useEffect, useRef, useState } from 'react'
 
 interface Props {
+  /** 顶部筛选框当前内容；按标题 / 工单号 / PR 号过滤看板卡片。 */
+  filterQuery: string
+  onFilterChange: (query: string) => void
   onRefresh: () => void
   /** host 正在重拉看板；为 true 时刷新图标转起来。 */
   refreshing: boolean
@@ -66,6 +69,8 @@ function releaseTitle(release: ReleaseStatus | undefined): string {
 }
 
 export function PanelHeader({
+  filterQuery,
+  onFilterChange,
   onRefresh,
   refreshing,
   scope,
@@ -113,7 +118,35 @@ export function PanelHeader({
   }
 
   return (
-    <div className="flex h-8 shrink-0 items-center justify-end gap-1 border-b border-[var(--vscode-panel-border)] px-2">
+    <div className="flex h-8 shrink-0 items-center gap-1 border-b border-[var(--vscode-panel-border)] px-2">
+      <div className="relative mr-auto flex items-center">
+        <Search size={12} className="pointer-events-none absolute left-2 opacity-60" />
+        <input
+          type="text"
+          value={filterQuery}
+          onChange={e => onFilterChange(e.target.value)}
+          onKeyDown={(e) => {
+            if (e.key === 'Escape') {
+              e.stopPropagation()
+              onFilterChange('')
+            }
+          }}
+          placeholder="筛选：标题 / 工单号 / PR 号"
+          aria-label="筛选工单"
+          className="h-6 w-56 rounded border border-[var(--vscode-input-border,transparent)] bg-[var(--vscode-input-background)] pl-6 pr-6 text-xs text-[var(--vscode-input-foreground)] outline-none placeholder:text-[var(--vscode-input-placeholderForeground)] focus:border-[var(--vscode-focusBorder)]"
+        />
+        {filterQuery !== '' && (
+          <button
+            type="button"
+            onClick={() => onFilterChange('')}
+            title="清空筛选"
+            aria-label="清空筛选"
+            className="absolute right-1 flex h-4 w-4 items-center justify-center rounded hover:bg-[var(--vscode-toolbar-hoverBackground)]"
+          >
+            <X size={11} />
+          </button>
+        )}
+      </div>
       <div ref={menuRef} className="relative">
         <button
           type="button"