✨ 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/App.tsx

@@ -13,6 +13,7 @@ import { ToastStack } from './components/ToastStack'
 import { useIssues } from './hooks/useIssues'
 import { useManagedSessions } from './hooks/useManagedSessions'
 import { useProfiles } from './hooks/useProfiles'
+import { filterIssues } from './lib/issueFilter'
 import { compareIssuesInColumn } from './lib/issueSort'
 import { COLUMN_ORDER } from './types'
 
@@ -127,6 +128,9 @@ export function App() {
     setShowNewIssueModal(false)
   }
 
+  // 顶部筛选框内容。纯前端过滤，不影响拖拽与详情面板拿到的全量列表。
+  const [filterQuery, setFilterQuery] = useState('')
+
   // Drop selectedId if it's no longer present after issues refresh.
   const readyIssues = state.status === 'ready' ? state.issues : null
   useEffect(() => {
@@ -153,13 +157,15 @@ export function App() {
 
   // Issues partitioned by column, in COLUMN_ORDER. Used for arrow navigation.
   // 排序与看板视觉一致：完成列按 PR 合并时间降序，其余列按工单号降序。
+  // 键盘导航只在筛选后可见的卡片之间走，和看板显示保持一致。
   const ordered = useMemo<Issue[][]>(() => {
     if (!readyIssues)
       return []
+    const visible = filterIssues(readyIssues, filterQuery)
     return COLUMN_ORDER.map(col =>
-      readyIssues.filter(i => i.column === col).sort((a, b) => compareIssuesInColumn(col, a, b)),
+      visible.filter(i => i.column === col).sort((a, b) => compareIssuesInColumn(col, a, b)),
     )
-  }, [readyIssues])
+  }, [readyIssues, filterQuery])
 
   // Resolved selected issue (or null) for the detail panel.
   const selectedIssue = useMemo<Issue | null>(() => {
@@ -312,6 +318,8 @@ export function App() {
       {state.status === 'loading' && (
         <>
           <PanelHeader
+            filterQuery={filterQuery}
+            onFilterChange={setFilterQuery}
             onRefresh={refresh}
             refreshing={refreshing}
             scope={scope}
@@ -339,6 +347,8 @@ export function App() {
       {state.status === 'ready' && (
         <>
           <PanelHeader
+            filterQuery={filterQuery}
+            onFilterChange={setFilterQuery}
             onRefresh={refresh}
             refreshing={refreshing}
             scope={scope}
@@ -361,6 +371,7 @@ export function App() {
             <div className="min-h-0 flex-1 overflow-hidden">
               <KanbanBoard
                 issues={state.issues}
+                filterQuery={filterQuery}
                 onIssuesChange={setIssues}
                 onCreateIssue={() => setShowNewIssueModal(true)}
                 selectedId={selectedId}
@@ -445,6 +456,8 @@ export function App() {
       {state.status === 'error' && (
         <>
           <PanelHeader
+            filterQuery={filterQuery}
+            onFilterChange={setFilterQuery}
             onRefresh={refresh}
             refreshing={refreshing}
             scope={scope}