- Add `--verbose`/`-v` flag; gate all diagnostic stderr output behind it
- Add `--no-uuid`, `--no-source`, `--no-location`, `--no-description`,
`--no-conference-url` flags to suppress individual INFO lines
- Add `--sort` option (`asc`, `desc`, `original`) replacing hardcoded
descending sort
- Add `--source` option to override calendar name (single-file only)
- Introduce `Config` module with global `ref` flags set at startup from
CLI args
- Add `Utils.warn` helper that writes to stderr only when
`Config.verbose` is set
- Normalise all diagnostic messages to a consistent format (`Warning:
... (UID: ...)`)
- Remove `debug_print_of_recurrence_and_skip`; inline skip at each call
site
- Fix `add_common_part` to always emit a trailing `\\\n `
continuation line
