claude_refactor_v3: Test real trainer loading before training loop + Add log.md

src/training/trainer_new.py

@@ -230,7 +230,7 @@ class Trainer:
     def train(self) -> None:
         """Full pipeline: setup → build → train → evaluate → cleanup."""
         self._validate_backbone()
-        #! clear_vram()
+        clear_vram()
         set_seed(self.pipeline_cfg.seed)
         self._setup_output_dir()
         self._setup_tracker()