Add VRAM cleanup (gc + empty_cache) before training start

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/training/train_gtauav.py

@@ -200,6 +200,17 @@ def _evaluate(
     return metrics
 
 
+def _clear_vram() -> None:
+    """Free VRAM from previous runs before starting."""
+    import gc
+    gc.collect()
+    if torch.cuda.is_available():
+        torch.cuda.empty_cache()
+        torch.cuda.reset_peak_memory_stats()
+        allocated = torch.cuda.memory_allocated() / 1e9
+        LOGGER.info("🧹 VRAM cleared. Current usage: %.2f GB", allocated)
+
+
 def train(cfg: TrainConfigGTAUAV) -> None:
     """Run full training loop."""
     coloredlogs.install(
@@ -207,6 +218,7 @@ def train(cfg: TrainConfigGTAUAV) -> None:
         logger=LOGGER,
         fmt="%(asctime)s %(name)s %(levelname)s %(message)s",
     )
+    _clear_vram()
     _set_seed(cfg.seed)
     output_dir = Path(cfg.output_dir)
     output_dir.mkdir(parents=True, exist_ok=True)