fix: parse multipart uploads for shop-chat files and chat-room images

Same root cause as the shop logo fix: these two routes still expected
req.files.<field> (the removed express-form-data pattern) with no
multer middleware in front of them, so:
- POST /shop-chat/:shopId/messages/file always rejected with "فایل
  الزامی است" even when a valid image/video was sent.
- POST /chat-rooms room creation silently dropped room_image, and
  would lose all text fields (title, visibility, ...) whenever the
  request was multipart (i.e. whenever an image was attached).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

routes/application/chat-rooms/index.js

@@ -36,8 +36,25 @@ const roomMessageUpload = multer({
   limits: { fileSize: 200 * 1024 * 1024 }
 }).single('file')
 
+// همون باگ: createRoom منتظرِ req.files.room_image بود ولی این روت هیچ parserِ
+// multipart نداشت — پس ساختِ اتاق با عکس همیشه شکست می‌خورد (یا حتی بدونِ عکس،
+// اگه کلاینت همون درخواستِ multipart رو بدونِ فایل هم بفرسته، عنوانِ اتاق هم گم می‌شد)
+const roomImageTmpDir = '/tmp/modstagram-uploads'
+if (!fs.existsSync(roomImageTmpDir)) {
+  fs.mkdirSync(roomImageTmpDir, { recursive: true })
+}
+const roomImageUpload = multer({
+  storage: multer.diskStorage({
+    destination: (req, file, cb) => cb(null, roomImageTmpDir),
+    filename: (req, file, cb) => {
+      cb(null, `${Date.now()}-${crypto.randomUUID()}${path.extname(file.originalname || '')}`)
+    }
+  }),
+  limits: { fileSize: 20 * 1024 * 1024 }
+}).single('room_image')
+
 router.get('/', listRooms)
-router.post('/', createRoom)
+router.post('/', roomImageUpload, createRoom)
 router.get('/:roomId', getRoomDetail)
 router.post('/:roomId/join', joinRoom)
 router.post('/:roomId/members', addRoomMembers)