refactor: replace predicate-based event matching with collector pipeline

- Simplify `.ocamlformat` to use `default` profile with fewer overrides
- Extract shared types and utilities into a `remind_sync` library
  (`icalendar_augmented`, `ptime_augmented`, `timedesc_augmented`,
  `result_augmented`, `utf8`)
- Replace `eventTransformer.ml` and the predicate system in
  `eventPredicates.ml` with a sequential collector pipeline
  (`collect_uuid`, `collect_summary`, `collect_start_end_duration`,
  etc.)
- Simplify `Remind.rem` to a flat record with `Timedesc` date/time
  fields and replace `rem_to_string` with a leaner `string_of_rem`
- Add `separate_master_and_recurrence` and `get_recurrence_id` helpers
  to `utils.ml`
- Wire `main.ml` to call `EventPredicates.remind_of_event` per UID group
  and print results directly
- Remove `eventTransformer` module from `bin/dune` and enable the
  `remind_sync` library dependency

bin/dune

@@ -1,11 +1,11 @@
 (executable
  (public_name remind_sync)
  (name main)
- (modules main commandLine remind eventTransformer eventPredicates utils)
+ (modules main commandLine remind eventPredicates utils)
  (preprocess
   (pps ppx_deriving.show))
  (libraries
-  ;remind_sync
+  remind_sync
   cmdliner
   icalendar
   timedesc-tzdb.full