fix: 终端 PTY 尺寸同步

前端在 xterm fit/resize 后通过 WebSocket 发送 resize 控制消息，后端收到后调用 ChannelShell.setPtySize 触发远端重绘，修复 less/vim/top 等全屏程序只显示部分区域的问题。

同时补齐控制消息解析与 PTY resize 的单测，并修正失配的 SftpControllerTest 断言。

frontend/src/components/TerminalWidget.vue

@@ -1,11 +1,12 @@
 <script setup lang="ts">
 import { nextTick, ref, onMounted, onUnmounted, watch } from 'vue'
 import { Terminal } from 'xterm'
-import { AttachAddon } from '@xterm/addon-attach'
 import { FitAddon } from '@xterm/addon-fit'
 import { useAuthStore } from '../stores/auth'
 import 'xterm/css/xterm.css'
 
+const CONTROL_PREFIX = '__SSHMANAGER__:'
+
 const props = defineProps<{
   connectionId: number
   active?: boolean
@@ -15,10 +16,15 @@ const containerRef = ref<HTMLElement | null>(null)
 const status = ref<'connecting' | 'connected' | 'error'>('connecting')
 const errorMessage = ref('')
 
-let term: Terminal | null = null
-let fitAddon: FitAddon | null = null
+let term: Terminal | null = null
+let fitAddon: FitAddon | null = null
 let ws: WebSocket | null = null
 let resizeObserver: ResizeObserver | null = null
+let onDataDisposable: { dispose: () => void } | null = null
+let onResizeDisposable: { dispose: () => void } | null = null
+let resizeDebounceTimer = 0
+let lastSentCols = 0
+let lastSentRows = 0
 
 function fitTerminal() {
   fitAddon?.fit()
@@ -46,21 +52,67 @@ function getWsUrl(): string {
   return `${protocol}//${host}/ws/terminal?connectionId=${props.connectionId}&token=${encodeURIComponent(token)}`
 }
 
-function cleanup() {
-  if (resizeObserver && containerRef.value) {
-    resizeObserver.unobserve(containerRef.value)
-  }
-  resizeObserver = null
-  if (ws) {
-    ws.close()
-    ws = null
-  }
-  if (term) {
-    term.dispose()
-    term = null
-  }
-  fitAddon = null
-}
+function cleanup() {
+  if (resizeObserver && containerRef.value) {
+    resizeObserver.unobserve(containerRef.value)
+  }
+  resizeObserver = null
+
+  if (onDataDisposable) {
+    onDataDisposable.dispose()
+    onDataDisposable = null
+  }
+  if (onResizeDisposable) {
+    onResizeDisposable.dispose()
+    onResizeDisposable = null
+  }
+  clearTimeout(resizeDebounceTimer)
+  resizeDebounceTimer = 0
+
+  if (ws) {
+    ws.close()
+    ws = null
+  }
+  if (term) {
+    term.dispose()
+    term = null
+  }
+  fitAddon = null
+}
+
+function sendResize(cols: number, rows: number) {
+  if (!ws || ws.readyState !== WebSocket.OPEN) return
+  if (!cols || !rows) return
+  if (cols === lastSentCols && rows === lastSentRows) return
+  lastSentCols = cols
+  lastSentRows = rows
+  ws.send(CONTROL_PREFIX + JSON.stringify({ type: 'resize', cols, rows }))
+}
+
+function scheduleResize(cols: number, rows: number) {
+  clearTimeout(resizeDebounceTimer)
+  resizeDebounceTimer = window.setTimeout(() => {
+    sendResize(cols, rows)
+  }, 80)
+}
+
+async function handleWsMessage(data: unknown) {
+  if (!term) return
+
+  if (typeof data === 'string') {
+    term.write(data)
+    return
+  }
+  if (data instanceof ArrayBuffer) {
+    const text = new TextDecoder('utf-8').decode(new Uint8Array(data))
+    term.write(text)
+    return
+  }
+  if (data instanceof Blob) {
+    const text = await data.text()
+    term.write(text)
+  }
+}
 
 onMounted(() => {
   const authStore = useAuthStore()
@@ -72,7 +124,7 @@ onMounted(() => {
 
   if (!containerRef.value) return
 
-  term = new Terminal({
+  term = new Terminal({
     cursorBlink: true,
     theme: {
       background: '#0f172a',
@@ -85,10 +137,14 @@ onMounted(() => {
     fontFamily: 'Menlo, Monaco, "Courier New", monospace',
   })
 
-  fitAddon = new FitAddon()
-  term.loadAddon(fitAddon)
+  fitAddon = new FitAddon()
+  term.loadAddon(fitAddon)
   term.open(containerRef.value)
   fitTerminal()
+
+  onResizeDisposable = term.onResize(({ cols, rows }) => {
+    scheduleResize(cols, rows)
+  })
 
   try {
     ws = new WebSocket(getWsUrl())
@@ -98,11 +154,19 @@ onMounted(() => {
     return
   }
 
-  ws.onopen = () => {
+  ws.onopen = () => {
     status.value = 'connected'
-    const attachAddon = new AttachAddon(ws!)
-    term!.loadAddon(attachAddon)
     refreshTerminalLayout()
+    scheduleResize(term!.cols, term!.rows)
+  }
+
+  onDataDisposable = term.onData((data) => {
+    if (!ws || ws.readyState !== WebSocket.OPEN) return
+    ws.send(data)
+  })
+
+  ws.onmessage = (ev) => {
+    void handleWsMessage(ev.data)
   }
 
   ws.onerror = () => {
@@ -120,6 +184,9 @@ onMounted(() => {
 
   resizeObserver = new ResizeObserver(() => {
     fitTerminal()
+    if (term) {
+      scheduleResize(term.cols, term.rows)
+    }
   })
   resizeObserver.observe(containerRef.value)