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/eventPredicates.ml

@@ -52,7 +52,8 @@ let collect_start_end_duration rem ev : (Remind.rem, error) result =
           begin match ev.dtend_or_duration with
           | None -> { rem with Remind.date = day_start } |> Result.ok
           | Some (`Dtend (_, `Datetime _)) ->
-              skip (* Start is a date, end is a datetime: invalid case for all-day event *)
+              Utils.warn "Warning: DTSTART is DATE but DTEND is DATETIME, skipping (UID: %s)\n" rem.Remind.original_uuid;
+              skip
           | Some (`Dtend (_, `Date (year, month, day))) ->
               begin match Timedesc.Date.Ymd.make ~year ~month ~day with
               | Error e -> invalid_date "DTEND" e
@@ -96,7 +97,7 @@ let collect_start_end_duration rem ev : (Remind.rem, error) result =
               Ok rem
             end
           | `Date (_year, _month, _day) ->
-              (* Start is a datetime, end is a date: invalid case for timed event *)
+              Utils.warn "Warning: DTSTART is DATETIME but DTEND is DATE, skipping (UID: %s)\n" rem.Remind.original_uuid;
               skip
           end
       | Some (`Duration (_, duration)) ->
@@ -121,20 +122,15 @@ let yearly_simple_date rem ev : (Remind.rem, error) result =
   | Some _ -> Ok rem
   | None -> Ok rem
 
-let debug_print_of_recurrence_and_skip ev recurs =
-  let uid = Utils.get_uid ev in
-  Printf.eprintf "RRULE: %s\t\t\tUID: %s\n" (Icalendar.show_recurrence recurs) uid;
-  skip
-
 let simple_recurrence rem ev : (Remind.rem, error) result =
   match ev.rrule with
   | Some (_, (`Yearly, None, None, [])) -> Ok rem (* handled in yearly_simple_date *)
   | Some (_, ((`Weekly as freq), count_or_until, interval, recurs))
   | Some (_, ((`Daily as freq), count_or_until, interval, recurs)) ->
       begin if List.length rem.recurring > 0 then (
-        Printf.eprintf "Warning: skipping complex recurrence with EXDATE/RDATE/overrides, not supported\t\t\tUID: %s\n"
+        Utils.warn "Warning: complex recurrence with EXDATE/RDATE/overrides not supported, skipping (UID: %s)\n"
           (Utils.get_uid ev);
-        debug_print_of_recurrence_and_skip ev (freq, count_or_until, interval, recurs))
+        skip)
       else
         let days =
           ListLabels.filter_map recurs ~f:(function
@@ -162,8 +158,8 @@ let simple_recurrence rem ev : (Remind.rem, error) result =
   | Some (_, (`Monthly, count_or_until, interval, recurs)) ->
       begin match interval with
       | Some n when n > 1 ->
-          Printf.eprintf "Warning: MONTHLY INTERVAL=%d not supported\t\t\tUID: %s\n" n (Utils.get_uid ev);
-          debug_print_of_recurrence_and_skip ev (`Monthly, count_or_until, interval, recurs)
+          Utils.warn "Warning: MONTHLY INTERVAL=%d not supported, skipping (UID: %s)\n" n (Utils.get_uid ev);
+          skip
       | _ -> (
           let bymonthday =
             List.find_map
@@ -187,11 +183,13 @@ let simple_recurrence rem ev : (Remind.rem, error) result =
           in
           match pattern with
           | None ->
-              Printf.eprintf "Warning: MONTHLY with unsupported BYDAY\t\t\tUID: %s\n" (Utils.get_uid ev);
-              debug_print_of_recurrence_and_skip ev (`Monthly, count_or_until, interval, recurs)
+              Utils.warn "Warning: MONTHLY with unsupported BYDAY, skipping (UID: %s)\n" (Utils.get_uid ev);
+              skip
           | Some p -> Ok { rem with Remind.monthly = Some { count_or_until; interval; pattern = p } })
       end
-  | Some (_, recurs) -> debug_print_of_recurrence_and_skip ev recurs
+  | Some (_, recurs) ->
+      Utils.warn "Warning: unsupported recurrence rule, skipping (UID: %s)\n" (Utils.get_uid ev);
+      skip
   | None -> Ok rem
 
 let is_cancelled (ev : Icalendar.event) : bool =
@@ -219,7 +217,8 @@ let collect_overrides rem _ev : (Remind.rem, error) result =
         let exdates =
           match recur_id_opt with
           | None ->
-              Printf.eprintf "Warning: override event has no RECURRENCE-ID\t\t\tUID: %s\n" (Utils.get_uid override_ev);
+              Utils.warn "Warning: override event has no RECURRENCE-ID, skipping (UID: %s)\n"
+                (Utils.get_uid override_ev);
               exdates
           | Some date_or_dt -> date_or_dt :: exdates
         in
@@ -228,7 +227,7 @@ let collect_overrides rem _ev : (Remind.rem, error) result =
           else
             match build_override_rem rem.Remind.source override_ev with
             | Error _ ->
-                Printf.eprintf "Warning: could not build override REM\t\t\tUID: %s\n" (Utils.get_uid override_ev);
+                Utils.warn "Warning: could not build override REM, skipping (UID: %s)\n" (Utils.get_uid override_ev);
                 overrides
             | Ok override_rem -> override_rem :: overrides
         in