fix: crash in --llm-rerank output for model names without a dash

llm_model.split('-')[1] raises IndexError for any model tag that contains
no dash (e.g. an Ollama tag like 'qwen3:8b' or an OpenAI-compat route like
'spark/fast'), crashing locomo_bench.py at startup when --llm-rerank is
enabled and longmemeval_bench.py on the diary pre-compute path. Both sites
only build display strings, so print the full model tag instead of
guessing at a short name.

Hit in practice when pointing --llm-backend ollama at a LiteLLM gateway
with provider-prefixed model routes.

benchmarks/locomo_bench.py

@@ -665,7 +665,7 @@ def run_benchmark(
                 palace_cache = json.load(f)
             print(f"  Palace cache: {len(palace_cache)} room assignments loaded")
 
-    rerank_label = f" + LLM re-rank ({llm_model.split('-')[1]})" if llm_rerank_enabled else ""
+    rerank_label = f" + LLM re-rank ({llm_model})" if llm_rerank_enabled else ""
 
     print(f"\n{'=' * 60}")
     print("  MemPal × LoCoMo Benchmark")

benchmarks/longmemeval_bench.py

@@ -3015,7 +3015,7 @@ def run_benchmark(
 
         if unique_sessions and api_key and not skip_precompute:
             print(
-                f"  Diary ingest: pre-computing {len(unique_sessions)} sessions with {llm_model.split('-')[1]}..."
+                f"  Diary ingest: pre-computing {len(unique_sessions)} sessions with {llm_model}..."
             )
             done = 0
             cache_path = Path(diary_cache_file) if diary_cache_file else None