dsv4.1: vision tower and image preprocessing (#39668)

Co-authored-by: BBuf <1182563586@qq.com>
Co-authored-by: Yuhao Yang <47235274+yhyang201@users.noreply.github.com>

test/registered/unit/multimodal/test_processor_async_call_sites.py

@@ -154,6 +154,9 @@ def test_overrides_take_the_worker_pools_processor_clone():
 # explicitly so that adding a processor forces a decision instead of silently
 # leaving it at one-worker speed.
 _NO_WORKER_POOL_ROUTE = {
+    # Runs its own image preprocessing to keep the raw token ids the Engram
+    # hasher needs; the shared chain would re-tokenize them.
+    "deepseek_v41.py",
     "dots_note_omni.py",
     "inkling.py",
     "lightonocr.py",