Merge latest prod_v2 (FileList preview modal, EditModal tabs) into integration

prod_v2's inline preview modal and EditModal redesign conflicted with the
hardening branch's authenticated file API (urlOf/downloadUrl were removed
because <a href>/<img> cannot send the Authorization header).

- FileList: kept prod_v2's design (icons, preview modal, per-row actions)
  and adapted it — previews now fetch the bytes with a Bearer token and
  use a local objectURL (api.files.blobUrl), with revoke on close/unmount;
  the row download uses the authenticated onDownload.
- EditModal: took prod_v2's tabbed redesign wholesale (it already carried
  our globalSpecs, clean material name and target_project work) and
  converted its FileList to onDownload + loadPreview.
- AcceptModal: converted the remaining urlOf sites and removed duplicated
  file/date blocks the earlier merge had left outside the scroll body.
- api.ts: restored the global handle401 (definition + all four fetch
  sites) alongside the new blobUrl helper.

frontend/src/pages/Dashboard/AcceptModal.tsx

@@ -406,7 +406,8 @@ export function AcceptModal({ quoteId, onClose }: AcceptModalProps) {
                       toast.error(err instanceof Error ? err.message : "حذف فاکتور ناموفق بود"),
                     )
                   }
-                  urlOf={(a) => (a.id ? api.files.downloadUrl(q.id, "invoice", a.id) : null)}
+                  onDownload={(a) => api.files.download(q.id, "invoice", a.id!, a.name)}
+                  loadPreview={(a) => api.files.blobUrl(q.id, "invoice", a.id!)}
                 />
               </div>
 
@@ -424,7 +425,8 @@ export function AcceptModal({ quoteId, onClose }: AcceptModalProps) {
                       toast.error(err instanceof Error ? err.message : "حذف پیش‌فاکتور ناموفق بود"),
                     )
                   }
-                  urlOf={(a) => (a.id ? api.files.downloadUrl(q.id, "proforma", a.id) : null)}
+                  onDownload={(a) => api.files.download(q.id, "proforma", a.id!, a.name)}
+                  loadPreview={(a) => api.files.blobUrl(q.id, "proforma", a.id!)}
                   label="افزودن پیش‌فاکتور"
                 />
               </div>
@@ -439,49 +441,6 @@ export function AcceptModal({ quoteId, onClose }: AcceptModalProps) {
 
           </div>
 
-        {/* فاکتورهای اصلی */}
-        <div className="border-t border-line pt-3">
-          <div className="mb-1 text-[13px] font-bold">فاکتورهای اصلی (چند فایل):</div>
-          <FileList
-            files={invoices}
-            onChange={setInvoices}
-            upload={(f) => api.files.upload(q.id, "invoice", f)}
-            onDelete={(a) =>
-              a.id &&
-              void api.files.remove(q.id, "invoice", a.id).catch((err) =>
-                toast.error(err instanceof Error ? err.message : "حذف فاکتور ناموفق بود"),
-              )
-            }
-            onDownload={(a) => api.files.download(q.id, "invoice", a.id!, a.name)}
-          />
-        </div>
-
-        {/* پیش‌فاکتورها */}
-        <div className="border-t border-line pt-3">
-          <div className="mb-1 text-[13px] font-bold">پیش‌فاکتورها (چند فایل):</div>
-          <FileList
-            files={proformas}
-            onChange={setProformas}
-            upload={(f) => api.files.upload(q.id, "proforma", f)}
-            onDelete={(a) =>
-              a.id &&
-              void api.files.remove(q.id, "proforma", a.id).catch((err) =>
-                toast.error(err instanceof Error ? err.message : "حذف پیش‌فاکتور ناموفق بود"),
-              )
-            }
-            onDownload={(a) => api.files.download(q.id, "proforma", a.id!, a.name)}
-            label="افزودن پیش‌فاکتور"
-          />
-        </div>
-
-        {/* تاریخ و زمان پذیرش */}
-        <div className="border-t border-line pt-3">
-          <div className="field max-w-xs">
-            <label>تاریخ و زمان پذیرش</label>
-            <JalaliDatePicker value={acceptDate} onChange={setAcceptDate} placeholder="تاریخ و ساعت" withTime />
-          </div>
-        </div>
-
         {/* فوتر ثابت */}
         <div className="px-6 py-4 bg-white border-t border-line shrink-0 z-10">
           <DialogFooter className="flex w-full gap-3 sm:justify-end">