feat: fatura PDF, hizmet/yazılım atama dosya ekleri

- /print/invoices/[id] sayfası: A4 fatura yazdırma/PDF (AutoPrint + PrintActionBar)
- Fatura detayı header'ına PDF butonu eklendi (Yazdır yerine)
- Appwrite Storage: entity-attachments bucket (20MB, şifreli)
- Appwrite Tables: attachments collection (tenantId, entityType, entityId, fileId, name, size, mimeType)
- attachment-actions.ts: fetchAttachmentsAction, uploadAttachmentAction, deleteAttachmentAction
- AttachmentsPanel bileşeni: dosya yükleme/listeleme/silme, edit modunda görünür
- Hizmet ve yazılım atama form sheet'lerine AttachmentsPanel entegrasyonu
- /api/files/[attachmentId]: güvenli proxy indirme (tenant doğrulama + admin key ile Appwrite'a istek)

src/app/(dashboard)/software/components/assignment-form-sheet.tsx

@@ -28,6 +28,7 @@ import {
   updateAssignmentAction,
 } from "@/lib/appwrite/software-actions";
 import { initialSoftwareState } from "@/lib/appwrite/software-types";
+import { AttachmentsPanel } from "@/components/attachments-panel";
 import type { AssignmentRow, CustomerOption, SoftwareOption } from "./types";
 
 type Props = {
@@ -202,6 +203,14 @@ export function AssignmentFormSheet({
                 placeholder="Lisans bilgileri, özel koşullar"
               />
             </div>
+
+            {/* Ekler */}
+            {isEdit && assignment && (
+              <AttachmentsPanel
+                entityType="customer_software"
+                entityId={assignment.id}
+              />
+            )}
           </div>
 
           <SheetFooter className="border-t bg-muted/30 px-6 pt-4">