refactor: move UploadChunk exports from event.py to _upload module

Re-export UploadChunk and UploadChunkIterator directly from
reflex._upload instead of re-importing them through reflex.event,
removing the eager import_module call at module load time.

Author: FarhanAliRaza

pyi_hashes.json

@@ -1,5 +1,5 @@
 {
-  "reflex/__init__.pyi": "276759cf35be6503c710e2203405adb6",
+  "reflex/__init__.pyi": "a0266c47111e9af7f340186013c7a31e",
   "reflex/components/__init__.pyi": "ac05995852baa81062ba3d18fbc489fb",
   "reflex/components/base/__init__.pyi": "16e47bf19e0d62835a605baa3d039c5a",
   "reflex/components/base/app_wrap.pyi": "22e94feaa9fe675bcae51c412f5b67f1",

reflex/__init__.py

@@ -297,12 +297,14 @@
     "config": ["Config", "DBConfig"],
     "constants": ["Env"],
     "constants.colors": ["Color"],
+    "_upload": [
+        "UploadChunk",
+        "UploadChunkIterator",
+    ],
     "event": [
         "event",
         "EventChain",
         "EventHandler",
-        "UploadChunk",
-        "UploadChunkIterator",
         "call_script",
         "call_function",
         "run_script",

reflex/event.py

@@ -7,7 +7,6 @@
 from base64 import b64encode
 from collections.abc import Callable, Mapping, Sequence
 from functools import lru_cache, partial
-from importlib import import_module
 from typing import (
     TYPE_CHECKING,
     Annotated,
@@ -1101,11 +1100,6 @@ def as_event_spec(self, handler: EventHandler) -> EventSpec:
 upload_files_chunk = UploadFilesChunk
 
 
-_upload_module = import_module("reflex._upload")
-UploadChunk = _upload_module.UploadChunk
-UploadChunkIterator = _upload_module.UploadChunkIterator
-
-
 # Special server-side events.
 def server_side(name: str, sig: inspect.Signature, **kwargs) -> EventSpec:
     """A server-side event.
@@ -2468,8 +2462,6 @@ class EventNamespace:
 
     # File Upload
     FileUpload = FileUpload
-    UploadChunk = UploadChunk
-    UploadChunkIterator = UploadChunkIterator
     UploadFilesChunk = UploadFilesChunk
 
     # Type Aliases