- date_to_epoch, iso_week_info, weeks_in_month: replaced unsafe libc
(mktime, strftime, localtime_r) with chrono NaiveDate and IsoWeek
- epoch_to_local: replaced unsafe libc localtime_r with chrono Local
- New util.rs with memory_subdir() helper: ensures subdir exists and
propagates errors instead of silently ignoring them
- Removed three duplicate agent_results_dir() definitions across
digest.rs, consolidate.rs, enrich.rs
- load_digest_files, parse_all_digest_links, find_consolidation_reports
now return Result to properly propagate directory creation errors
Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>
