Make tune trial budget resumable

src/aituner/cli.py

@@ -126,6 +126,8 @@ def cmd_study_tune(args: argparse.Namespace) -> int:
     executed: list[dict[str, object]] = []
     for idx in range(max_trials):
         state = store.load_state(study.study_id)
+        if state.next_trial_index > max_trials:
+            break
         window, requests = load_trace_requests(study, study_spec_path=spec_path)
         window_summary = summarize_window(requests, window)
         harness_context = (
@@ -169,7 +171,10 @@ def cmd_study_tune(args: argparse.Namespace) -> int:
                 ensure_ascii=False,
             )
         elif proposal_files:
-            proposal_source = proposal_files[idx]
+            proposal_index = state.next_trial_index - 1
+            if proposal_index >= len(proposal_files):
+                break
+            proposal_source = proposal_files[proposal_index]
             proposal_text = proposal_source.read_text(encoding="utf-8")
             proposal_name = proposal_source.stem
         else: