* feat: add reflect mode to LoComo benchmark and improve reflect agent
- Replace think mode with reflect mode in LoComo benchmark using reflect_async with Budget.HIGH
- Add --question-index CLI flag to run a single question by its index
- Track and display original question index in logs and visualizer
- Update visualizer to show reflect mode results
Reflect agent improvements:
- tool_recall: always fetch chunks (max_chunk_tokens=1000 min, non-optional)
- tool_search_observations: use include_source_facts=True instead of separate DB query
- Use model_dump() throughout to avoid manual error-prone dict conversion
- Enforce minimum 1000 tokens for max_tokens and max_chunk_tokens in _execute_tool
- Fix NoneType error when LLM passes null for mental_model_ids/observation_ids arrays
- Add non-conversational constraint to system prompt to prevent follow-up questions
- Fix recall_fn Callable type hint to include max_chunk_tokens parameter
- Fix main.py missing reranker_zeroentropy fields in HindsightConfig constructor
* fix: update tests for reflect tool API changes
- source_memory_ids -> source_fact_ids in test_search_observations (MemoryFact.model_dump() field name)
- Remove proof_count check (not in MemoryFact, was ObservationResult-specific)
- Remove max_results param from tool_recall call (no longer supported)
- Fix recall_result["count"] -> len(recall_result["memories"])
