feat(forecast): expose DOCX & PPTX export buttons in forecast UI

Add «Скачать .docx» (Word) and «Скачать .pptx» (PowerPoint) buttons to
ForecastExportButtons, alongside the existing .md/.json/Telegram controls.
The backend /forecast/export already renders both formats; they were just
not reachable from the UI. Both reuse the existing response.blob() →
triggerDownload path (correct for binary zip-based OOXML — never .text(),
which would corrupt the archive). Per-format loading state; 404 →
«Отчёт ещё не готов». No new deps (icons from lucide-react).

Part of #958.

frontend/src/components/site-finder/analysis/ForecastExportButtons.tsx

@@ -11,12 +11,17 @@
  * Backend (live on prod):
  *   GET /api/v1/parcels/{cad}/forecast/export?format=md   → text/markdown attachment
  *   GET /api/v1/parcels/{cad}/forecast/export?format=json → application/json attachment
+ *   GET /api/v1/parcels/{cad}/forecast/export?format=docx → Word (.docx) attachment
+ *   GET /api/v1/parcels/{cad}/forecast/export?format=pptx → PowerPoint (.pptx) attachment
  *   GET /api/v1/parcels/{cad}/forecast/export?format=tg   → text/plain inline (TG snippet)
  *   No forecast run → 404 → inline «Отчёт ещё не готов» (no crash, no console spam).
+ *
+ * docx/pptx are binary zip-based OOXML — they go through the SAME response.blob()
+ * path as md/json (never response.text(), which would corrupt the archive).
  */
 
 import { useEffect, useRef, useState } from "react";
-import { Download, Copy, Check } from "lucide-react";
+import { Download, Copy, Check, FileText, Presentation } from "lucide-react";
 
 import { API_BASE_URL } from "@/lib/api";
 import { triggerDownload } from "@/lib/download";
@@ -25,7 +30,9 @@ interface Props {
   cad: string;
 }
 
-type ExportFormat = "md" | "json";
+// Binary OOXML formats (docx/pptx) share md/json's blob download path; only the
+// query param + filename extension differ, so one discriminant covers them all.
+type ExportFormat = "md" | "json" | "docx" | "pptx";
 
 const NOT_READY_MSG = "Отчёт ещё не готов";
 const GENERIC_ERR_MSG = "Не удалось получить отчёт";
@@ -37,7 +44,7 @@ function sanitizeCad(cad: string): string {
   return cad.replace(/:/g, "_");
 }
 
-function exportUrl(cad: string, format: "md" | "json" | "tg"): string {
+function exportUrl(cad: string, format: ExportFormat | "tg"): string {
   return `${API_BASE_URL}/api/v1/parcels/${encodeURIComponent(
     cad,
   )}/forecast/export?format=${format}`;
@@ -136,6 +143,8 @@ export function ForecastExportButtons({ cad }: Props) {
 
   const mdLoading = downloadingFormat === "md";
   const jsonLoading = downloadingFormat === "json";
+  const docxLoading = downloadingFormat === "docx";
+  const pptxLoading = downloadingFormat === "pptx";
   const anyLoading = downloadingFormat !== null || tgLoading;
 
   return (
@@ -176,6 +185,26 @@ export function ForecastExportButtons({ cad }: Props) {
           onClick={() => void handleDownload("json")}
           icon={<Download size={14} strokeWidth={1.5} />}
         />
+
+        <ExportButton
+          label="Скачать .docx"
+          loadingLabel="Загрузка…"
+          loading={docxLoading}
+          disabled={anyLoading}
+          ariaLabel="Скачать отчёт прогноза в формате Word (.docx)"
+          onClick={() => void handleDownload("docx")}
+          icon={<FileText size={14} strokeWidth={1.5} />}
+        />
+
+        <ExportButton
+          label="Скачать .pptx"
+          loadingLabel="Загрузка…"
+          loading={pptxLoading}
+          disabled={anyLoading}
+          ariaLabel="Скачать отчёт прогноза в формате PowerPoint (.pptx)"
+          onClick={() => void handleDownload("pptx")}
+          icon={<Presentation size={14} strokeWidth={1.5} />}
+        />
       </div>
 
       {error && (