feat(files): preview attachments via short-lived signed URLs

Downloads require an Authorization header, which <iframe>/<img> cannot
send. The previous blob: workaround broke under download managers (IDM
hooks blob URLs, fails to resolve them, and leaves a 0-byte file) and in
Chrome's mobile emulation, which has no inline PDF plugin.

Backend:
- preview_token.py: HMAC-signed token bound to one (quote, kind, file)
  with a 5-minute TTL, keyed off an existing secret
- GET /quotes/{id}/preview-url/{kind}/{attachment} mints the URL
- the two file GET routes accept a Bearer session OR the signed ?t= token
  (they leave the global auth dep, so the other six file routes now carry
  it explicitly — nothing is open by omission)

Frontend:
- api.files.previewUrl() replaces the blob helper
- shared FilePreviewModal + useFilePreview; FileList and the dashboard
  quote card both use it
- PDFs render with the browser's native viewer on desktop and pdf.js on
  canvas where no inline viewer exists (mobile); pdf.js is fed the bytes
  in memory so no PDF URL is exposed for a download manager to intercept
- removed the per-attachment download buttons on the dashboard card and
  the modal header

Ops:
- nginx: explicit MIME types (.mjs as text/javascript) — a module worker
  served as octet-stream is refused and crashed the page
- frontend service bypasses the nginx entrypoint, whose apk manifest call
  hangs when the package mirror is unreachable (502s)

frontend/src/components/FileList.tsx

@@ -1,7 +1,8 @@
-import { useEffect, useRef, useState } from "react";
+import { useRef, useState } from "react";
 import { toast } from "sonner";
-import { Eye, Download, Trash2, X, FileText, Image as ImageIcon, ExternalLink } from "lucide-react";
+import { Eye, Download, Trash2, FileText, Image as ImageIcon } from "lucide-react";
 import type { Attachment } from "../lib/types";
+import { FilePreviewModal, isImageFile, isPdfFile } from "./FilePreviewModal";
 
 export interface FileListProps {
   files: Attachment[];
@@ -18,14 +19,6 @@ export interface FileListProps {
   label?: string;
 }
 
-const isImageFile = (name: string = "") => {
-  return /\.(jpe?g|png|webp|gif|svg|bmp)$/i.test(name.toLowerCase());
-};
-
-const isPdfFile = (name: string = "") => {
-  return /\.pdf$/i.test(name.toLowerCase());
-};
-
 // مدیریت چند فاکتور: آپلود مستقیم، پیش‌نمایش آنلاین تصویر/PDF و دانلود
 export function FileList({
   files,
@@ -39,21 +32,6 @@ export function FileList({
   const inputRef = useRef<HTMLInputElement | null>(null);
   const [previewItem, setPreviewItem] = useState<{ url: string; name: string } | null>(null);
   const [loadingPreview, setLoadingPreview] = useState<string | null>(null);
-  // آخرین objectURL ساخته‌شده — برای آزادسازی مطمئن (جلوگیری از نشت حافظه)
-  const previewUrlRef = useRef<string | null>(null);
-
-  const revokePreviewUrl = () => {
-    if (previewUrlRef.current) {
-      try {
-        URL.revokeObjectURL(previewUrlRef.current);
-      } catch {
-        /* آدرس نامعتبر — نادیده بگیر */
-      }
-      previewUrlRef.current = null;
-    }
-  };
-
-  useEffect(() => revokePreviewUrl, []);
 
   const remove = (i: number) => {
     const removed = files[i];
@@ -76,7 +54,8 @@ export function FileList({
     if (added.length) onChange([...files, ...added]);
   };
 
-  // پیش‌نمایش: بایت‌ها را با توکن می‌گیریم و به شکل objectURL نشان می‌دهیم
+  // پیش‌نمایش: یک URL امضاشده‌ی کوتاه‌عمر می‌گیریم (نه blob) تا
+  // دانلودمنیجرها آن را شکار نکنند و <iframe>/<img> درست بارگذاری شود.
   const handleOpenPreview = async (inv: Attachment) => {
     if (!loadPreview) return;
     if (!inv.id) {
@@ -86,8 +65,6 @@ export function FileList({
     setLoadingPreview(inv.id);
     try {
       const url = await loadPreview(inv);
-      revokePreviewUrl();
-      previewUrlRef.current = url;
       setPreviewItem({ url, name: inv.name });
     } catch (err) {
       toast.error(err instanceof Error ? err.message : "بارگذاری پیش‌نمایش ناموفق بود");
@@ -96,10 +73,7 @@ export function FileList({
     }
   };
 
-  const closePreview = () => {
-    revokePreviewUrl();
-    setPreviewItem(null);
-  };
+  const closePreview = () => setPreviewItem(null);
 
   return (
     <div className="space-y-2">
@@ -201,94 +175,9 @@ export function FileList({
         </button>
       </div>
 
-      {/* پنجره مودال پیش‌نمایش (Preview Modal) */}
+      {/* مودال پیش‌نمایش — کامپوننت مشترک با کارت پیشنهاد در داشبورد */}
       {previewItem && (
-        <div
-          className="fixed inset-0 z-[80] flex items-center justify-center bg-black/60 p-3 sm:p-5 backdrop-blur-xs animate-in fade-in duration-200"
-          onClick={closePreview}
-        >
-          <div
-            className="flex flex-col w-full max-w-4xl max-h-[90vh] rounded-2xl border border-gray-200 bg-white shadow-2xl overflow-hidden"
-            onClick={(e) => e.stopPropagation()}
-          >
-            {/* هدر پیش‌نمایش */}
-            <div className="flex items-center justify-between border-b border-gray-100 px-4 py-3 bg-white">
-              <div className="flex items-center gap-2 min-w-0">
-                {isImageFile(previewItem.name) ? (
-                  <ImageIcon className="h-4 w-4 shrink-0 text-blue-600" />
-                ) : (
-                  <FileText className="h-4 w-4 shrink-0 text-rose-600" />
-                )}
-                <span className="text-xs sm:text-sm font-bold text-gray-900 truncate">
-                  {previewItem.name}
-                </span>
-              </div>
-
-              <div className="flex items-center gap-1.5 shrink-0">
-                <a
-                  href={previewItem.url}
-                  download={previewItem.name}
-                  className="inline-flex items-center gap-1 rounded-lg border border-gray-200 bg-white px-2.5 py-1 text-xs font-semibold text-gray-700 hover:bg-gray-50 hover:text-gray-900 transition-colors shadow-2xs"
-                  title="دانلود فاکتور"
-                >
-                  <Download className="h-3.5 w-3.5" />
-                  <span className="hidden xs:inline">دانلود فاکتور</span>
-                </a>
-
-                <a
-                  href={previewItem.url}
-                  target="_blank"
-                  rel="noreferrer"
-                  className="flex h-7 w-7 items-center justify-center rounded-lg border border-gray-200 text-gray-600 hover:bg-gray-50 hover:text-gray-900 transition-colors shadow-2xs"
-                  title="باز کردن در برگه جدید"
-                >
-                  <ExternalLink className="h-3.5 w-3.5" />
-                </a>
-
-                <button
-                  type="button"
-                  onClick={closePreview}
-                  className="flex h-7 w-7 items-center justify-center rounded-lg text-gray-400 hover:bg-gray-100 hover:text-gray-700 transition-colors ms-1"
-                  title="بستن"
-                >
-                  <X className="h-4 w-4" />
-                </button>
-              </div>
-            </div>
-
-            {/* بدنه نمایش فایل */}
-            <div className="flex-1 overflow-auto p-3 sm:p-4 bg-gray-50/70 flex items-center justify-center min-h-[300px]">
-              {isImageFile(previewItem.name) ? (
-                <img
-                  src={previewItem.url}
-                  alt={previewItem.name}
-                  className="max-h-[75vh] w-auto max-w-full rounded-lg object-contain shadow-xs border border-gray-200 bg-white"
-                />
-              ) : isPdfFile(previewItem.name) ? (
-                <iframe
-                  src={previewItem.url}
-                  title={previewItem.name}
-                  className="h-[75vh] w-full rounded-lg border border-gray-200 bg-white shadow-xs"
-                />
-              ) : (
-                <div className="flex flex-col items-center justify-center gap-3 p-8 text-center bg-white rounded-xl border border-gray-200 shadow-xs">
-                  <FileText className="h-12 w-12 text-gray-400" />
-                  <div className="text-xs text-gray-600">
-                    امکان نمایش پیش‌نمایش زنده برای این فرمت فایل وجود ندارد.
-                  </div>
-                  <a
-                    href={previewItem.url}
-                    download={previewItem.name}
-                    className="inline-flex items-center gap-1.5 rounded-lg bg-blue-600 px-3.5 py-1.5 text-xs font-semibold text-white hover:bg-blue-700 transition-colors"
-                  >
-                    <Download className="h-3.5 w-3.5" />
-                    دانلود فایل
-                  </a>
-                </div>
-              )}
-            </div>
-          </div>
-        </div>
+        <FilePreviewModal url={previewItem.url} name={previewItem.name} onClose={closePreview} />
       )}
     </div>
   );