refactored and condensed technical documentation and comments across the codebase to improve readability

lib/extensions/date_time.dart

@@ -23,11 +23,9 @@ extension IsSameDay on DateTime {
   bool isSameOrAfter(DateTime other) => isSameDateTime(other) || isAfter(other);
 }
 
-/// Calendar-aware day arithmetic. `DateTime.add(Duration(days: n))` adds
-/// `n * 24h` of real-world time, which on local DateTimes silently drifts by
-/// ±1h across DST transitions — so 7 days from "Monday 00:00 CEST" before a
-/// DST fall-back lands at "Sunday 23:00 CET", shifting the entire next week
-/// onto the wrong calendar day. [addDays]/[subtractDays] normalize through
+/// Calendar-aware day arithmetic. `DateTime.add(Duration(days: n))` adds real
+/// time that drifts ±1h across DST, shifting a whole week onto the wrong
+/// calendar day. [addDays]/[subtractDays] normalize through
 /// `DateTime(year, month, day + n)` so the wall-clock fields stay fixed.
 extension CalendarDayArithmetic on DateTime {
   DateTime addDays(int days) => DateTime(