refactor(edit): redesign the custom recurrence picker (#42)

Rebuild the custom step of the recurrence picker so complex-but-supported
rules (e.g. "every 2 weeks on Mon+Tue") are discoverable and legible,
rather than buried in a ragged stack of mismatched controls.

- Add a live, human-readable summary of the rule as it is built, via the
  existing recurrenceText humanizer.
- Group interval + frequency into one tonal card; the frequency is now a
  SingleChoiceSegmentedButtonRow (all four units visible) instead of a
  dropdown.
- Reveal the weekday picks with AnimatedVisibility and house them, the
  "every" controls, and the ends group in consistent 16dp-inset grouped
  cards; the count field folds into the bottom of the ends run.

No behaviour, domain, or RRULE changes: parse/render logic and the set of
expressible rules are unchanged. The EXDATE half of #42 is deferred.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditScreen.kt

@@ -1382,8 +1382,43 @@ private fun RecurrencePickerDialog(
             )
         } else {
             Column(
-                verticalArrangement = Arrangement.spacedBy(8.dp),
+                modifier = Modifier.fillMaxWidth(),
-                modifier = Modifier.padding(horizontal = 24.dp),
+                verticalArrangement = Arrangement.spacedBy(16.dp),
+            ) {
+                // A live, human-readable read-out of the rule being built, so the
+                // effect of the controls below is never a guess.
+                Text(
+                    text = recurrenceText(
+                        SimpleRecurrence(
+                            freq = freq,
+                            interval = interval ?: 1,
+                            end = customEnd ?: RecurrenceEnd.Never,
+                            byDays = if (freq == RecurrenceFreq.Weekly) {
+                                daysMask.toDaySet()
+                            } else {
+                                emptySet()
+                            },
+                        ).toRRule(),
+                        locale,
+                    ),
+                    style = MaterialTheme.typography.titleMedium,
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(horizontal = 16.dp),
+                )
+
+                // How often: an interval amount plus a frequency segmented row —
+                // all four units on show, no unit hidden behind a dropdown.
+                Surface(
+                    color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                    shape = groupedShape(Position.Alone),
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(horizontal = 16.dp),
+                ) {
+                    Column(
+                        modifier = Modifier.padding(16.dp),
+                        verticalArrangement = Arrangement.spacedBy(16.dp),
                     ) {
                         Row(verticalAlignment = Alignment.CenterVertically) {
                             Text(
@@ -1396,31 +1431,52 @@ private fun RecurrencePickerDialog(
                                 onValueChange = { intervalText = it },
                                 placeholder = "1",
                             )
-                    Spacer(Modifier.width(12.dp))
+                        }
-                    DialogUnitDropdown(
+                        SingleChoiceSegmentedButtonRow(modifier = Modifier.fillMaxWidth()) {
-                        label = stringResource(recurrenceUnitLabel(freq)),
+                            RecurrenceFreq.entries.forEachIndexed { index, entry ->
-                        entries = RecurrenceFreq.entries.map {
+                                SegmentedButton(
-                            stringResource(recurrenceUnitLabel(it))
+                                    selected = freq == entry,
-                        },
+                                    onClick = { freq = entry },
-                        onPick = { freq = RecurrenceFreq.entries[it] },
+                                    shape = SegmentedButtonDefaults.itemShape(
+                                        index, RecurrenceFreq.entries.size,
+                                    ),
+                                    label = { Text(stringResource(recurrenceUnitLabel(entry))) },
                                 )
                             }
-                if (freq == RecurrenceFreq.Weekly) {
+                        }
+                    }
+                }
+
+                // Weekday picks — only meaningful on a weekly rule.
+                AnimatedVisibility(visible = freq == RecurrenceFreq.Weekly) {
+                    Surface(
+                        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                        shape = groupedShape(Position.Alone),
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .padding(horizontal = 16.dp),
+                    ) {
                         WeekdayToggleRow(
                             selected = daysMask.toDaySet(),
                             onToggle = { day -> daysMask = daysMask xor day.toMaskBit() },
                             locale = locale,
+                            modifier = Modifier.padding(16.dp),
                         )
                     }
+                }
+
+                // Ends: a connected never / on-a-date / after-N group, the count
+                // field folding into the bottom of the run when chosen.
+                Column {
                     Text(
                         text = stringResource(R.string.event_edit_recurrence_ends),
-                    style = MaterialTheme.typography.bodyMedium,
+                        style = MaterialTheme.typography.labelLarge,
                         color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.padding(start = 16.dp, bottom = 8.dp),
                     )
-            }
                     GroupedRow(
                         title = stringResource(R.string.event_edit_recurrence_end_never),
-                position = positionOf(0, 3),
+                        position = Position.Top,
                         selected = endMode == RecurrenceEndMode.Never,
                         onClick = { endMode = RecurrenceEndMode.Never },
                     )
@@ -1432,7 +1488,7 @@ private fun RecurrencePickerDialog(
                                     .withLocale(locale).format(it.toJavaLocalDate())
                             }
                         },
-                position = positionOf(1, 3),
+                        position = Position.Middle,
                         selected = endMode == RecurrenceEndMode.Until,
                         onClick = {
                             endMode = RecurrenceEndMode.Until
@@ -1441,14 +1497,25 @@ private fun RecurrencePickerDialog(
                     )
                     GroupedRow(
                         title = stringResource(R.string.event_edit_recurrence_end_count),
-                position = positionOf(2, 3),
+                        position = if (endMode == RecurrenceEndMode.Count) {
+                            Position.Middle
+                        } else {
+                            Position.Bottom
+                        },
                         selected = endMode == RecurrenceEndMode.Count,
                         onClick = { endMode = RecurrenceEndMode.Count },
                     )
                     if (endMode == RecurrenceEndMode.Count) {
+                        Surface(
+                            color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                            shape = groupedShape(Position.Bottom),
+                            modifier = Modifier
+                                .fillMaxWidth()
+                                .padding(horizontal = 16.dp),
+                        ) {
                             Row(
                                 verticalAlignment = Alignment.CenterVertically,
-                    modifier = Modifier.padding(horizontal = 24.dp, vertical = 4.dp),
+                                modifier = Modifier.padding(16.dp),
                             ) {
                                 DialogAmountField(
                                     value = countText,
@@ -1464,6 +1531,9 @@ private fun RecurrencePickerDialog(
                         }
                     }
                 }
+            }
+        }
+    }
 
     if (showUntilPicker) {
         CalendarDatePickerDialog(
@@ -1489,6 +1559,7 @@ private fun WeekdayToggleRow(
     selected: Set<DayOfWeek>,
     onToggle: (DayOfWeek) -> Unit,
     locale: Locale,
+    modifier: Modifier = Modifier,
 ) {
     val days = remember(locale) {
         val first = WeekFields.of(locale).firstDayOfWeek.toKotlinDayOfWeek()
@@ -1496,7 +1567,7 @@ private fun WeekdayToggleRow(
     }
     Row(
         horizontalArrangement = Arrangement.SpaceBetween,
-        modifier = Modifier.fillMaxWidth(),
+        modifier = modifier.fillMaxWidth(),
     ) {
         days.forEach { day ->
             val isSelected = day in selected