feat(datepicker): more sane datetime config

refactored global settings; (partial!) quickfix for time inconsistency between selected time and input value

frontend/src/utils/form/datepicker.js

@@ -10,18 +10,37 @@ const DATEPICKER_INITIALIZED_CLASS = 'datepicker--initialized';
 
 const DATEPICKER_CONFIG = {
   'global': {
+    // minimize overlaps with other date inputs
     position: 'right',
-    locale: 'de',  // TODO: hardcoded
-    weekStart: 1,  // TODO: hardcoded
-    stayOpen: true,  // to prevent the instance from closing when selecting a date before selecting a time
+
+    // set default time to 00:00:00
+    // this is a workaround to prevent inconsistent dates in input field and datepicker
+    timeHours: 0,
+    timeMinutes: 0,
+    timeSeconds: 0,
+
+    // german settings
+    // TODO: hardcoded, get from current language / settings
+    locale: 'de',
+    weekStart: 1,
+    dateFormat: 'dd.mm.YYYY',
+
+    // prevent the instance from closing when selecting a date before selecting a time
+    stayOpen: true,
+
+    // hide the close button (we handle closing the datepicker manually by clicking outside)
     closeButton: false,
-    dateFormat: 'dd.mm.YYYY',  // TODO: hardcoded, get from setting
+
+    // disable the decades view because nobody will ever need it (i.e. cap the switch to the more relevant year view)
+    viewDecades: false,
   },
   'datetime-local': {},
   'date': {
+    // disable date picker
     timeFormat: false,
   },
   'time': {
+    // disable time picker
     dateFormat: false,
   },
 };