docs: 更新需求文档至v0.5并归档开发进度；修复大文件上传与二维码海报

- 需求文档升级到 v0.5：补充二维码海报保存文件名默认格式、大文件上传三层限制（IIS+ASP.NET+前端）部署约束、新增第11章开发进度状态归档（已上线功能/已修复缺陷/已知限制/后续优化）
- 后端 FileController.Upload 增加 [RequestFormLimits(MultipartBodyLengthLimit=220_200_960)]，修复>128MB multipart 上传被拒
- 前端 UploadView 二维码海报：修正 drawImage 缩放错位、顶部logo/标题垂直居中、分区标题间距、大小与有效期分行显示；保存文件名改为 文传易取件码-取件码(原文件名)-流水号.png
- 新增部署脚本：apply_backend.ps1 / force_dll.ps1（app_offline 解锁DLL）/ ftp_fe.ps1 / ftp_diag.ps1 / ftp_apply.ps1 / _diag/check_dll.ps1

(部署手册 IIS部署与FTP发布.md 仅含编码/BOM 差异，未纳入本次提交)

frontend/src/views/UploadView.vue

@@ -18,6 +18,20 @@
       </div>
     </div>
 
+    <!-- 微信内置浏览器提示 -->
+    <div
+      v-if="isWeChat && showWeChatTip"
+      class="mb-4 px-4 py-3 flex items-start gap-2 text-[13px] rounded-2xl border-2 border-[#FFD591] bg-[#FFF7E8]"
+    >
+      <div class="flex-1 text-[#8A6213] leading-relaxed">
+        微信内上传与下载会受限（无法从聊天选择文件、下载需跳转外部浏览器）。建议点击右上角「···」→「在浏览器打开」。
+        <button class="text-[#2D6CFF] font-medium underline underline-offset-2" @click="copySiteLink">复制链接</button>
+      </div>
+      <button class="text-[#C0A06B] shrink-0" @click="showWeChatTip = false">
+        <t-icon name="close" :size="16" />
+      </button>
+    </div>
+
     <!-- 上传大卡片 -->
     <div
       v-if="!result"
@@ -48,12 +62,17 @@
 
       <!-- 文件模式 -->
       <div v-if="!textMode">
-        <input ref="fileInput" type="file" class="hidden" @change="onFileChange" />
         <div
           v-if="!selectedFile"
-          class="py-7 flex flex-col items-center justify-center gap-2.5 cursor-pointer text-center"
-          @click="openPicker"
+          class="relative py-7 flex flex-col items-center justify-center gap-2.5 cursor-pointer text-center"
         >
+          <!-- 原生 file input 透明铺满上传区：不显示实体按钮，用户点击上传区时直接点到 input，由系统弹出选择器 -->
+          <input
+            ref="fileInput"
+            type="file"
+            class="absolute inset-0 z-10 w-full h-full opacity-0 cursor-pointer"
+            @change="onFileChange"
+          />
           <div class="w-14 h-14 rounded-2xl bg-gradient-to-br from-[#2D6CFF] to-[#00B4FF]/80 grid place-items-center text-white shadow-card">
             <t-icon name="cloud-upload" :size="26" />
           </div>
@@ -287,6 +306,35 @@ const expires = [
 
 const textMode = ref(false)
 const fileInput = ref<HTMLInputElement | null>(null)
+const isWeChat = ref(false)
+const showWeChatTip = ref(true)
+
+// 微信内置浏览器上传/下载受限，提供复制链接引导用户在外部浏览器打开
+function copySiteLink() {
+  const url = location.href
+  const ok = () => MessagePlugin.success('链接已复制，请到浏览器中粘贴打开')
+  if (navigator.clipboard?.writeText) {
+    navigator.clipboard.writeText(url).then(ok).catch(() => fallbackCopy(url))
+  } else {
+    fallbackCopy(url)
+  }
+}
+function fallbackCopy(text: string) {
+  const ta = document.createElement('textarea')
+  ta.value = text
+  ta.style.position = 'fixed'
+  ta.style.opacity = '0'
+  ta.style.left = '-9999px'
+  document.body.appendChild(ta)
+  ta.select()
+  try {
+    document.execCommand('copy')
+    MessagePlugin.success('链接已复制，请到浏览器中粘贴打开')
+  } catch {
+    MessagePlugin.error('复制失败，请长按地址栏手动复制')
+  }
+  document.body.removeChild(ta)
+}
 const selectedFile = ref<File | null>(null)
 const pastedText = ref('')
 const expireHours = ref(24)
@@ -322,10 +370,6 @@ const canUpload = computed(() => {
   return !!selectedFile.value && !passwordError.value && !tagError.value
 })
 
-function openPicker() {
-  fileInput.value?.click()
-}
-
 function onFileChange(e: Event) {
   const input = e.target as HTMLInputElement
   if (input.files?.length) handleFile(input.files[0])
@@ -524,14 +568,16 @@ async function buildPoster(d: UploadResult): Promise<string> {
   roundRect(ctx, 48, 24, 52, 52, 14)
   ctx.fill()
   ctx.fillStyle = '#FFFFFF'
+  ctx.textBaseline = 'middle'
   ctx.textAlign = 'center'
   ctx.font = `bold 26px ${FONT}`
-  ctx.fillText('传', 74, 37)
+  ctx.fillText('传', 74, 50) // logo 圆块 24-76 范围的中线
   ctx.textAlign = 'left'
-  ctx.fillText('文传易', 118, 26)
+  ctx.fillText('文传易', 118, 36) // 与 logo 中线略上对齐（视觉与"免登录"副标题更平衡）
   ctx.font = `14px ${FONT}`
   ctx.fillStyle = 'rgba(255,255,255,0.9)'
-  ctx.fillText('免登录，传文件，真容易', 118, 60)
+  ctx.fillText('免登录，传文件，真容易', 118, 64)
+  ctx.textBaseline = 'top' // 恢复默认给后续 sectionTitle 等使用
 
   // 成功提示
   ctx.fillStyle = '#00B578'
@@ -542,12 +588,12 @@ async function buildPoster(d: UploadResult): Promise<string> {
   // 分区小标题
   const sectionTitle = (text: string, y: number) => {
     ctx.fillStyle = '#2D6CFF'
-    roundRect(ctx, 44, y + 2, 4, 15, 2)
+    roundRect(ctx, 38, y + 2, 4, 15, 2)
     ctx.fill()
     ctx.fillStyle = '#1F2329'
     ctx.textAlign = 'left'
     ctx.font = `600 15px ${FONT}`
-    ctx.fillText(text, 60, y)
+    ctx.fillText(text, 66, y)
   }
 
   let y = 164
@@ -598,8 +644,8 @@ async function buildPoster(d: UploadResult): Promise<string> {
   sectionTitle('文件信息', y)
   y += 36
 
-  // 文件信息卡
-  const cardH = 20 + 32 + nameLines.length * 24 + 14
+  // 文件信息卡（精确高度：上下各 16 padding + 文件名 N*24 + 大小行 24 + 有效期行 24）
+  const cardH = 16 + nameLines.length * 24 + 24 + 24 + 16
   ctx.fillStyle = '#F4F8FF'
   roundRect(ctx, 44, y, W - 88, cardH, 16)
   ctx.fill()
@@ -614,14 +660,23 @@ async function buildPoster(d: UploadResult): Promise<string> {
     cy += 24
     ctx.fillText(nameLines[i], 130, cy)
   }
-  cy += 30
+  // 大小（单独一行）
+  cy += 28
   ctx.fillStyle = '#8A9099'
   ctx.font = `14px ${FONT}`
-  ctx.fillText('大小 / 有效期', 62, cy)
+  ctx.fillText('大小', 62, cy)
+  ctx.fillStyle = '#1F2329'
+  ctx.font = `15px ${FONT}`
+  ctx.fillText(formatSize(d.size), 130, cy)
+  // 有效期（单独一行）
+  cy += 24
+  ctx.fillStyle = '#8A9099'
+  ctx.font = `14px ${FONT}`
+  ctx.fillText('有效期', 62, cy)
   ctx.fillStyle = '#1F2329'
   ctx.font = `15px ${FONT}`
   const expireText = d.isPermanent ? '永久有效' : `至 ${formatDateTime(d.expiresAt)}`
-  ctx.fillText(`${formatSize(d.size)} · ${expireText}`, 150, cy)
+  ctx.fillText(expireText, 130, cy)
 
   // 取件码标签（与大码拉开间距避免重叠）
   let codeY = y + cardH + 28
@@ -650,14 +705,15 @@ async function buildPoster(d: UploadResult): Promise<string> {
 
   // 动态画布高度（按实际内容，消除底部大留白）
   // 注意：重设 canvas.height 会清空画布内容，必须先备份再画回
+  // 关键：drawImage 必须显式指定目标尺寸=backup 尺寸，否则浏览器会按新 canvas.height 缩放整张图，导致文字比例全乱
   const newH = qrY + qrSize + 14 + 40
-  if (canvas.height !== newH) {
+  if (Math.abs(canvas.height - newH) > 1) {
     const backup = document.createElement('canvas')
     backup.width = canvas.width
     backup.height = canvas.height
     backup.getContext('2d')!.drawImage(canvas, 0, 0)
     canvas.height = newH
-    canvas.getContext('2d')!.drawImage(backup, 0, 0)
+    canvas.getContext('2d')!.drawImage(backup, 0, 0, backup.width, backup.height)
   }
 
   return canvas.toDataURL('image/png')
@@ -697,9 +753,14 @@ async function copyText(text: string) {
 async function downloadQr() {
   if (!result.value) return
   posterDataUrl.value = await buildPoster(result.value)
+  // 保存文件名：文传易取件码-取件码(原文件名)-流水号.png（清洗 Windows 非法字符）
+  const safeName = (result.value.originalName || '')
+    .replace(/[\\/:*?"<>|\u0000-\u001f]/g, '_')
+    .replace(/\s+/g, ' ')
+    .trim() || '未命名'
   const a = document.createElement('a')
   a.href = posterDataUrl.value
-  a.download = `文传易取件凭证_${result.value.pickCode}.png`
+  a.download = `文传易取件码-${result.value.pickCode}(${safeName})-${result.value.id}.png`
   a.click()
 }
 
@@ -715,6 +776,9 @@ function formatDateTime(s: string | null) {
   return s.replace('T', ' ').slice(0, 16)
 }
 
-onMounted(() => window.addEventListener('paste', onPaste))
+onMounted(() => {
+  isWeChat.value = /MicroMessenger/i.test(navigator.userAgent)
+  window.addEventListener('paste', onPaste)
+})
 onUnmounted(() => window.removeEventListener('paste', onPaste))
 </script>