Add --run flag to sol dream for single prompt execution
Enables iterating on individual prompts without re-running the entire
dream pipeline. Key changes:
- Add --run NAME to execute a single generator or agent by name
- Add --facet NAME to target specific facet for multi-facet agents
- Validate schedule compatibility (segment prompts require --segment)
- Check agent end states and surface errors in single-prompt mode
- Add iso_date() utility to replace inline YYYYMMDD formatting
Usage examples:
sol dream --day 20250129 --run activity --segment 120000_300 --force
sol dream --day 20250129 --run timeline --force
sol dream --day 20250129 --run facet_newsletter --facet work
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>