- Add assertion, pass_criteria, fail_criteria, check_type to AtomicControlCandidate dataclass
- Parse MCP fields from LLM output in _process_pass0b_control
- Store MCP fields in generation_metadata JSON for later use by MCP scanner
- Fields default to empty when not present (backward-compatible with old prompts)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>