06d75f613c
- Add format_envelope_markdown() function in invariants.rs for rich markdown formatting of ActionEnvelope facts - Add format_yaml_value_markdown() helper for recursive YAML value display - Update execute_plan_read() to append rulespec and envelope sections - Update execute_plan_write() to append envelope section alongside rulespec - Add 3 tests for format_envelope_markdown (empty, with facts, null values) When plan_read or plan_write is called, the output now includes: - Plan YAML (as before) - Rulespec section (if rulespec.yaml exists) with invariants grouped by source - Envelope section (if envelope.yaml exists) with facts in readable format Missing files show placeholder text rather than errors.