feat(attach): 附件可配置限额、流式落盘与分阶段上传

管理端可配类型/体积；上传改流式避免整文件进内存；发帖先选再传并拦截未上传提交；提高 Next proxy 体积上限。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/PostAttachments.tsx

@@ -9,6 +9,7 @@ import {
   postAttachmentDownloadURL,
   type PostAttachment,
 } from "@/lib/api";
+import { fileExtBadge, fileKind } from "@/lib/fileKind";
 import { toast } from "@/lib/toast";
 import Modal from "@/components/Modal";
 
@@ -22,52 +23,6 @@ function formatPoints(n: number) {
   return n.toLocaleString("zh-CN");
 }
 
-function fileExt(name: string) {
-  const i = name.lastIndexOf(".");
-  if (i <= 0 || i === name.length - 1) return "FILE";
-  const ext = name.slice(i + 1).replace(/[^a-zA-Z0-9]/g, "");
-  if (!ext || ext.length > 5) return "FILE";
-  return ext.toUpperCase();
-}
-
-function fileKind(name: string, mime: string): "image" | "archive" | "doc" | "media" | "file" {
-  const m = (mime || "").toLowerCase();
-  const ext = (name.split(".").pop() || "").toLowerCase();
-  if (
-    m.startsWith("image/") ||
-    ["png", "jpg", "jpeg", "gif", "webp", "svg", "bmp", "avif", "ico", "heic"].includes(ext)
-  ) {
-    return "image";
-  }
-  if (
-    m.includes("zip") ||
-    m.includes("rar") ||
-    m.includes("7z") ||
-    m.includes("compress") ||
-    ["zip", "rar", "7z", "tar", "gz", "bz2", "xz"].includes(ext)
-  ) {
-    return "archive";
-  }
-  if (
-    m.startsWith("audio/") ||
-    m.startsWith("video/") ||
-    ["mp3", "wav", "flac", "aac", "ogg", "mp4", "mkv", "webm", "mov", "avi"].includes(ext)
-  ) {
-    return "media";
-  }
-  if (
-    m.includes("pdf") ||
-    m.includes("word") ||
-    m.includes("text") ||
-    m.includes("sheet") ||
-    m.includes("excel") ||
-    ["pdf", "doc", "docx", "txt", "md", "xls", "xlsx", "ppt", "pptx", "csv"].includes(ext)
-  ) {
-    return "doc";
-  }
-  return "file";
-}
-
 /** 把已拿到的文件交给浏览器下载栏（付费首次须先 fetch 才能处理 402） */
 function triggerBrowserDownload(blob: Blob, filename: string) {
   const url = URL.createObjectURL(blob);
@@ -92,7 +47,7 @@ function AttachmentMeta({
   return (
     <>
       <span className="j13-att-type" data-kind={fileKind(a.name, a.mime)} aria-hidden>
-        {fileExt(a.name)}
+        {fileExtBadge(a.name)}
       </span>
       <span className="j13-att-main">
         <span className="j13-att-name">{a.name}</span>
@@ -312,7 +267,7 @@ export default function PostAttachments({
                 data-kind={fileKind(pending.name, pending.mime)}
                 aria-hidden
               >
-                {fileExt(pending.name)}
+                {fileExtBadge(pending.name)}
               </span>
               <div className="min-w-0">
                 <p className="j13-att-pay-name">{pending.name}</p>