feat(processors): Add ToBatchProcessor to multiple policy processors

- Integrated ToBatchProcessor into various policy processors to handle observation batching.
- Updated make functions for act, diffusion, pi0, pi0fast, sac, smolvla, tdmpc, and vqbet processors to include the new batching functionality.
- Ensured consistency across all processor implementations for improved data handling.

src/lerobot/policies/act/processor_act.py

@@ -19,6 +19,7 @@ from lerobot.policies.act.configuration_act import ACTConfig
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -33,6 +34,7 @@ def make_act_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/diffusion/processor_diffusion.py

@@ -20,6 +20,7 @@ from lerobot.policies.diffusion.configuration_diffusion import DiffusionConfig
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -34,6 +35,7 @@ def make_diffusion_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/pi0/processor_pi0.py

@@ -20,6 +20,7 @@ from lerobot.policies.pi0.configuration_pi0 import PI0Config
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -34,6 +35,7 @@ def make_pi0_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/pi0fast/processor_pi0fast.py

@@ -20,6 +20,7 @@ from lerobot.policies.pi0.configuration_pi0 import PI0Config
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -34,6 +35,7 @@ def make_pi0_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/sac/processor_sac.py

@@ -21,6 +21,7 @@ from lerobot.policies.sac.configuration_sac import SACConfig
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -35,6 +36,7 @@ def make_sac_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/smolvla/processor_smolvla.py

@@ -19,6 +19,7 @@ from lerobot.policies.smolvla.configuration_smolvla import SmolVLAConfig
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -33,6 +34,7 @@ def make_smolvla_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/tdmpc/processor_tdmpc.py

@@ -20,6 +20,7 @@ from lerobot.policies.tdmpc.configuration_tdmpc import TDMPCConfig
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -34,6 +35,7 @@ def make_tdmpc_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(

src/lerobot/policies/vqbet/processor_vqbet.py

@@ -21,6 +21,7 @@ from lerobot.policies.vqbet.configuration_vqbet import VQBeTConfig
 from lerobot.processor import (
     NormalizerProcessor,
     RobotProcessor,
+    ToBatchProcessor,
     UnnormalizerProcessor,
 )
 
@@ -35,6 +36,7 @@ def make_vqbet_processor(
         NormalizerProcessor(
             features=config.output_features, norm_map=config.normalization_mapping, stats=dataset_stats
         ),
+        ToBatchProcessor(),
     ]
     output_steps = [
         UnnormalizerProcessor(