feat(security): JWT required on every API route, gated dev fallback, role checks

- main.py: global get_current_user dependency on all routers except
  /auth/login and /health; prod fail-fast startup guard rejects wildcard
  CORS, default credentials, DEV_LOGIN_ENABLED
- inventory/pm: X-User-Role header identity fallback now only active when
  PROCUREMENT_DEV_LOGIN_ENABLED=true (was unconditional in production)
- item_decisions writes + attachment deletes: require_role(
  procurement_manager, admin) — require_role was defined but never used
- config.py: ENVIRONMENT flag, comma-separated CORS_ORIGINS, no default
  Casdoor client secret/admin password, DEV_LOGIN_ENABLED=false
- frontend: authenticated file downloads (Bearer + blob) — <a href> links
  cannot send the token; FileList/QuoteDetail/AcceptModal/EditModal/
  PurchaseHistory converted; DEV_LOGIN_ENABLED build arg defaults false
- smoke tests authenticate via POST /auth/login (SMOKE_USER/SMOKE_PASSWORD)
- traefik: security headers, API rate limit, 12MB body cap (prod overlay)
- nginx client_max_body_size aligned to 12MB

frontend/src/lib/api.ts

@@ -1282,8 +1282,31 @@ export const api = {
     remove: async (quoteId: string, kind: FileKind, id: string): Promise<void> => {
       await deleteData(`/quotes/${quoteId}/${kind}/${id}`);
     },
-    downloadUrl: (quoteId: string, kind: FileKind, id: string): string =>
-      `${BASE_URL}/quotes/${quoteId}/${kind}/${id}`,
+    // دانلود احراز هویت‌شده: <a href> توکن Authorization نمی‌فرستد، پس بایت‌ها
+    // را با توکن می‌گیریم و به شکل blob در مرورگر ذخیره می‌کنیم.
+    download: async (quoteId: string, kind: FileKind, id: string, fileName: string): Promise<void> => {
+      let res: Response;
+      try {
+        res = await fetch(`${BASE_URL}/quotes/${quoteId}/${kind}/${id}`, {
+          headers: authHeaders(),
+        });
+      } catch {
+        throw new ApiError("اتصال به سرور برقرار نشد — آیا بک‌اند در دسترس است؟", 0);
+      }
+      if (!res.ok) throw new ApiError(faHttpError(res.status, "خطای سرور"), res.status);
+      const blob = await res.blob();
+      const url = URL.createObjectURL(blob);
+      try {
+        const a = document.createElement("a");
+        a.href = url;
+        a.download = fileName || "attachment";
+        document.body.appendChild(a);
+        a.click();
+        a.remove();
+      } finally {
+        URL.revokeObjectURL(url);
+      }
+    },
   },
 
   // ---------- برندها (از بک‌اند) ----------