feat: add EditEventScreen with calendar and chat mode support

Add a unified event editor that works in two modes:
- Calendar mode: Create/edit events directly via EventService API
- Chat mode: Edit AI-proposed events before confirming them

The chat mode allows users to modify proposed events (title, time,
recurrence) and persists changes both locally and to the server.

New components: DateTimePicker, ScrollableDropdown, useDropdownPosition
New API: PUT /api/chat/messages/:messageId/proposal

packages/shared/src/utils/dateHelpers.ts

@@ -34,3 +34,15 @@ export function getDay(
   result.setHours(hour, minute, 0, 0);
   return result;
 }
+
+/**
+ * Check if an event spans multiple days.
+ * Compares dates at midnight to determine if start and end are on different calendar days.
+ */
+export function isMultiDayEvent(start: Date, end: Date): boolean {
+  const startDate = new Date(start);
+  const endDate = new Date(end);
+  startDate.setHours(0, 0, 0, 0);
+  endDate.setHours(0, 0, 0, 0);
+  return startDate.getTime() !== endDate.getTime();
+}

packages/shared/src/utils/formatters.ts

@@ -46,3 +46,26 @@ export function formatDateWithWeekday(date: Date): string {
     year: "numeric",
   });
 }
+
+/**
+ * Format date as DD.MM. (short, without year)
+ */
+export function formatDateShort(date: Date): string {
+  const d = new Date(date);
+  return d.toLocaleDateString("de-DE", {
+    day: "2-digit",
+    month: "2-digit",
+  });
+}
+
+/**
+ * Format date with weekday short as "Mo., DD.MM."
+ */
+export function formatDateWithWeekdayShort(date: Date): string {
+  const d = new Date(date);
+  return d.toLocaleDateString("de-DE", {
+    weekday: "short",
+    day: "2-digit",
+    month: "2-digit",
+  });
+}

packages/shared/src/utils/index.ts

@@ -1,3 +1,3 @@
 export * from "./dateHelpers";
-export * from "./rruleHelpers";
 export * from "./formatters";
+export * from "./rruleHelpers";

packages/shared/src/utils/rruleHelpers.ts

@@ -1,49 +1,29 @@
-import { rrulestr, Frequency } from "rrule";
+/**
+ * RRULE building and parsing helpers.
+ */
 
-export interface ParsedRRule {
-  freq: string; // "YEARLY", "MONTHLY", "WEEKLY", "DAILY", etc.
-  until?: Date;
-  count?: number;
-  interval?: number;
-  byDay?: string[]; // ["MO", "WE", "FR"]
-}
+export type RepeatType = "Tag" | "Woche" | "Monat" | "Jahr";
 
-const FREQ_NAMES: Record<Frequency, string> = {
-  [Frequency.YEARLY]: "YEARLY",
-  [Frequency.MONTHLY]: "MONTHLY",
-  [Frequency.WEEKLY]: "WEEKLY",
-  [Frequency.DAILY]: "DAILY",
-  [Frequency.HOURLY]: "HOURLY",
-  [Frequency.MINUTELY]: "MINUTELY",
-  [Frequency.SECONDLY]: "SECONDLY",
+const REPEAT_TYPE_TO_FREQ: Record<RepeatType, string> = {
+  Tag: "DAILY",
+  Woche: "WEEKLY",
+  Monat: "MONTHLY",
+  Jahr: "YEARLY",
 };
 
 /**
- * Parses an RRULE string and extracts the relevant fields.
- * Handles both with and without "RRULE:" prefix.
+ * Build an RRULE string from repeat count and type.
+ *
+ * @param repeatType - The type of repetition (Tag, Woche, Monat, Jahr)
+ * @param interval - The interval between repetitions (default: 1)
+ * @returns RRULE string like "FREQ=WEEKLY;INTERVAL=2"
  */
-export function parseRRule(ruleString: string): ParsedRRule | null {
-  if (!ruleString) {
-    return null;
+export function buildRRule(repeatType: RepeatType, interval: number = 1): string {
+  const freq = REPEAT_TYPE_TO_FREQ[repeatType];
+
+  if (interval <= 1) {
+    return `FREQ=${freq}`;
   }
 
-  try {
-    // Ensure RRULE: prefix is present
-    const normalized = ruleString.startsWith("RRULE:")
-      ? ruleString
-      : `RRULE:${ruleString}`;
-
-    const rule = rrulestr(normalized);
-    const options = rule.options;
-
-    return {
-      freq: FREQ_NAMES[options.freq] || "UNKNOWN",
-      until: options.until || undefined,
-      count: options.count || undefined,
-      interval: options.interval > 1 ? options.interval : undefined,
-      byDay: options.byweekday?.map((d) => d.toString()) || undefined,
-    };
-  } catch {
-    return null;
-  }
+  return `FREQ=${freq};INTERVAL=${interval}`;
 }