implement chat messaging with event proposals

- Add functional chat with server communication and test responses
- Add ProposedEventCard component for confirm/reject actions
- Move Constants (Day, Month) from client to shared package
- Add dateHelpers utility for weekday calculations
- Extend Themes.tsx with button and text colors
- Update CLAUDE.md with current implementation status
- Add *.tsbuildinfo to .gitignore

packages/shared/src/index.ts

@@ -1 +1,2 @@
 export * from './models';
+export * from './utils';

packages/shared/src/models/Constants.ts

@@ -0,0 +1,39 @@
+export const MONTHS = [
+  "January",
+  "February",
+  "March",
+  "April",
+  "May",
+  "June",
+  "July",
+  "August",
+  "September",
+  "October",
+  "November",
+  "December",
+] as const;
+
+export type Month = (typeof MONTHS)[number];
+
+export const DAYS = [
+  "Monday",
+  "Tuesday",
+  "Wednesday",
+  "Thursday",
+  "Friday",
+  "Saturday",
+  "Sunday",
+] as const;
+
+export type Day = (typeof DAYS)[number];
+
+// Mapping for Date.getDay() which returns 0=Sunday, 1=Monday, etc.
+export const DAY_INDEX: Record<Day, number> = {
+  Sunday: 0,
+  Monday: 1,
+  Tuesday: 2,
+  Wednesday: 3,
+  Thursday: 4,
+  Friday: 5,
+  Saturday: 6,
+};

packages/shared/src/models/index.ts

@@ -1,3 +1,4 @@
 export * from './User';
 export * from './CalendarEvent';
 export * from './ChatMessage';
+export * from './Constants';

packages/shared/src/utils/dateHelpers.ts

@@ -0,0 +1,31 @@
+import { Day, DAY_INDEX } from '../models/Constants';
+
+/**
+ * Get a date for a specific weekday relative to today.
+ * @param day - The target day (e.g., "Friday")
+ * @param offset - 1 = next occurrence, 2 = the one after, -1 = last occurrence, etc.
+ * @param hour - Hour of day (0-23)
+ * @param minute - Minute (0-59)
+ */
+export function getDay(day: Day, offset: number, hour: number, minute: number): Date {
+  const today = new Date();
+  const currentDay = today.getDay();
+  const targetDay = DAY_INDEX[day];
+
+  let daysUntil = targetDay - currentDay;
+
+  if (offset > 0) {
+    // Future: if target is today or past, move to next week
+    if (daysUntil <= 0) daysUntil += 7;
+    daysUntil += (offset - 1) * 7;
+  } else if (offset < 0) {
+    // Past: if target is today or future, move to last week
+    if (daysUntil >= 0) daysUntil -= 7;
+    daysUntil += (offset + 1) * 7;
+  }
+
+  const result = new Date(today);
+  result.setDate(today.getDate() + daysUntil);
+  result.setHours(hour, minute, 0, 0);
+  return result;
+}

packages/shared/src/utils/index.ts

@@ -0,0 +1 @@
+export * from './dateHelpers';