feat(cli): add output control flags, sort order, and verbose mode

- 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

bin/commandLine.ml

@@ -14,12 +14,69 @@ let timezone =
   let doc = "Target timezone for output (e.g. Europe/Rome). Defaults to local timezone." in
   Arg.(value & opt (some string) None & info [ "timezone"; "z" ] ~docv:"TZ" ~doc)
 
+let verbose =
+  let doc = "Print diagnostic messages (skipped events, unsupported recurrences, etc.) on stderr." in
+  Arg.(value & flag & info [ "verbose"; "v" ] ~doc)
+
+let no_uuid =
+  let doc = "Omit the INFO line with the event UID from output." in
+  Arg.(value & flag & info [ "no-uuid" ] ~doc)
+
+let no_source =
+  let doc = "Omit the INFO line with the calendar source name from output." in
+  Arg.(value & flag & info [ "no-source" ] ~doc)
+
+let no_location =
+  let doc = "Omit the INFO line with the event location from output." in
+  Arg.(value & flag & info [ "no-location" ] ~doc)
+
+let no_description =
+  let doc = "Omit the INFO line with the event description from output." in
+  Arg.(value & flag & info [ "no-description" ] ~doc)
+
+let no_conference_url =
+  let doc = "Omit the INFO line with the conference URL from output." in
+  Arg.(value & flag & info [ "no-conference-url" ] ~doc)
+
+type sort_order = Asc | Desc | Original
+
+let sort_order_enum = [ ("asc", Asc); ("desc", Desc); ("original", Original) ]
+
+let sort =
+  let doc = "Output sort order by date: $(b,desc) (default), $(b,asc), or $(b,none) (file order)." in
+  Arg.(value & opt (enum sort_order_enum) Desc & info [ "sort" ] ~docv:"ORDER" ~doc)
+
+let source =
+  let doc = "Override the calendar source name used in INFO lines. Only valid when processing a single file." in
+  Arg.(value & opt (some string) None & info [ "source" ] ~docv:"NAME" ~doc)
+
+type cli_args = {
+  tz : string option;
+  verbose : bool;
+  no_uuid : bool;
+  no_source : bool;
+  no_location : bool;
+  no_description : bool;
+  no_conference_url : bool;
+  sort : sort_order;
+  source : string option;
+}
+
 let main_command f =
   let doc = "Convert iCalendar files to remind format" in
   let man = [] in
   Cmd.make (Cmd.info "ical2rem" ~version:(version_string ()) ~doc ~man)
   @@
-  let+ files = files and+ tz = timezone in
-  f tz files
+  let+ files = files
+  and+ tz = timezone
+  and+ verbose = verbose
+  and+ no_uuid = no_uuid
+  and+ no_source = no_source
+  and+ no_location = no_location
+  and+ no_description = no_description
+  and+ no_conference_url = no_conference_url
+  and+ sort = sort
+  and+ source = source in
+  f { tz; verbose; no_uuid; no_source; no_location; no_description; no_conference_url; sort; source } files
 
 let main f = Cmd.eval @@ main_command f