feat: skip_current.flag to cancel experiment and move to next

Create the flag file in the sweep output_root to skip the running
experiment at the next log interval (every 50 steps):
  touch /path/to/experiment/skip_current.flag

Scheduler marks it as 'skipped' in the summary and continues.
Skipped experiments are NOT resumed on restart (unlike failed ones).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nodes/selva_lora_scheduler.py

@@ -38,6 +38,7 @@ import folder_paths
 from .utils import SELVA_CATEGORY, get_device
 from .selva_lora_trainer import (
     SelvaLoraTrainer,
+    SkipExperiment,
     _prepare_dataset,
     _smooth_losses,
     _pil_to_tensor,
@@ -474,6 +475,18 @@ class SelvaLoraScheduler:
                     "start_step":   0,
                 })
 
+            except SkipExperiment as e:
+                duration = time.monotonic() - t_start
+                print(f"[LoRA Scheduler] Experiment '{exp_id}' skipped: {e}", flush=True)
+                exp_record["results"] = {
+                    "status":           "skipped",
+                    "error":            str(e),
+                    "duration_seconds": round(duration, 1),
+                }
+                _write_summary()
+                pbar_outer.update(1)
+                continue
+
             except Exception as e:
                 duration = time.monotonic() - t_start
                 print(f"[LoRA Scheduler] Experiment '{exp_id}' failed: {e}", flush=True)