Fix: full pi models support for transformer v5 (#2967)

* fix(pi): remove loss truncation

* fix(pi): remove state padding before tokenization

* fix(pi): fix image padding value

* fix from_pretrain

* add transformer v5 changes

* remove reference

* more fixes

* make it work

* add support for rest of pi family

* add pifast work

* more changes

* more changes

* more cleanup

* fix torch params

* dtype fix

* torch compile

* embed mismatch fix

* revert groot

* more nit fixes

* remove unused classes

* more fixes

* revert

* nit

* torch dtype warning fix

* but back dynamic renaming

* add tie embedding

---------

Co-authored-by: Yufei Sun <skieyfly@gmail.com>

tests/policies/pi0_pi05/test_pi0.py

@@ -24,7 +24,7 @@ import torch
 # Skip this entire module in CI
 pytestmark = pytest.mark.skipif(
     os.environ.get("CI") == "true" or os.environ.get("GITHUB_ACTIONS") == "true",
-    reason="This test requires local OpenPI installation and is not meant for CI",
+    reason="This test requires accepting the model license",
 )
 
 from lerobot.policies.factory import make_policy_config  # noqa: E402