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/remind.ml

@@ -164,10 +164,13 @@ let render_alarm (rem : rem) : alarm_rendering =
         end
 
 (* ── buffer primitives ────────────────────────────────────────── *)
-
 let add_rem b = Buffer.add_string b "REM "
-let add_uid b uuid = Buffer.add_string b (spf "\\\n    INFO \"UID: %s\" " uuid)
-let add_source b source = Buffer.add_string b (spf "\\\n    INFO \"Calendar: %s\" " (String.uppercase_ascii source))
+let add_uid b uuid = if not !Config.no_uuid then Buffer.add_string b (spf "\\\n    INFO \"UID: %s\" " uuid)
+
+let add_source b source =
+  if not !Config.no_source then
+    Buffer.add_string b (spf "\\\n    INFO \"Calendar: %s\" " (String.uppercase_ascii source))
+
 let add_date b date = Buffer.add_string b (Timedesc.Date.to_rfc3339 date)
 let add_weekday b wd = Buffer.add_string b (spf "%s " (string_of_weekday wd))
 
@@ -275,26 +278,28 @@ let add_msg b ?(alarm = empty_alarm) ?(timed = false) summary =
   Buffer.add_string b (spf " MSG %s\n" body)
 
 let add_location b loc =
-  match loc with
-  | Some loc -> begin
-      let loc = String.trim loc in
-      Buffer.add_string b (spf "\\\n    INFO \"Location: %s\" " (escape_msg loc))
-    end
-  | None -> ()
+  if not !Config.no_location then
+    match loc with
+    | Some loc ->
+        let loc = String.trim loc in
+        Buffer.add_string b (spf "\\\n    INFO \"Location: %s\" " (escape_msg loc))
+    | None -> ()
 
 let add_description b desc =
-  match desc with
-  | Some desc ->
-      let desc = String.trim desc in
-      Buffer.add_string b (spf "\\\n    INFO \"Description: %s\" " (escape_msg desc))
-  | None -> ()
+  if not !Config.no_description then
+    match desc with
+    | Some desc ->
+        let desc = String.trim desc in
+        Buffer.add_string b (spf "\\\n    INFO \"Description: %s\" " (escape_msg desc))
+    | None -> ()
 
 let add_url b url =
-  match url with
-  | Some url ->
-      let url = String.trim url in
-      Buffer.add_string b (spf "\\\n    INFO \"Url: %s\" " (escape_msg url))
-  | None -> ()
+  if not !Config.no_conference_url then
+    match url with
+    | Some url ->
+        let url = String.trim url in
+        Buffer.add_string b (spf "\\\n    INFO \"Url: %s\" " (escape_msg url))
+    | None -> ()
 
 let add_common_part b rem =
   add_rem b;
@@ -302,7 +307,8 @@ let add_common_part b rem =
   add_source b rem.source;
   add_location b rem.location;
   add_description b rem.description;
-  add_url b rem.conference_url
+  add_url b rem.conference_url;
+  Buffer.add_string b "\\\n    "
 
 let date_of_date_or_datetime (d : Icalendar.date_or_datetime) : Timedesc.Date.t =
   match d with