Add packages/common for shared utilities

Create new @reviq/common package with environment-agnostic utilities:
- Date formatting: formatDate, formatDateTime, formatLongDate,
  formatRelativeDate, formatRelativeTime
- User utilities: getUserInitials, formatRole

Consolidate date formatting from publisher-dashboard into shared package.
All utilities include comprehensive test coverage with bun:test.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/common/src/format-date.ts

@@ -0,0 +1,128 @@
+/**
+ * Date formatting utilities for consistent display across the app.
+ * Works in all JavaScript environments (browser, Node.js, Bun, etc.)
+ */
+
+type DateInput = string | Date;
+
+/**
+ * Safely convert a date input to a Date object.
+ */
+function toDate(date: DateInput): Date {
+  return typeof date === "string" ? new Date(date) : date;
+}
+
+/**
+ * Calculate the difference in days between two dates.
+ */
+function daysDiff(from: Date, to: Date): number {
+  const diffMs = to.getTime() - from.getTime();
+  return Math.floor(diffMs / (1000 * 60 * 60 * 24));
+}
+
+/**
+ * Format a date for display in tables and lists.
+ * @example formatDate("2024-01-15") // "Jan 15, 2024"
+ */
+export function formatDate(date: DateInput): string {
+  const d = toDate(date);
+  return d.toLocaleDateString("en-US", {
+    month: "short",
+    day: "numeric",
+    year: "numeric",
+  });
+}
+
+/**
+ * Format a date with time for detailed views.
+ * @example formatDateTime("2024-01-15T15:30:00") // "Jan 15, 2024, 3:30 PM"
+ */
+export function formatDateTime(date: DateInput): string {
+  const d = toDate(date);
+  return d.toLocaleDateString("en-US", {
+    month: "short",
+    day: "numeric",
+    year: "numeric",
+    hour: "numeric",
+    minute: "2-digit",
+  });
+}
+
+/**
+ * Format a date in long form.
+ * @example formatLongDate("2024-01-15") // "January 15, 2024"
+ */
+export function formatLongDate(date: DateInput): string {
+  const d = toDate(date);
+  return d.toLocaleDateString("en-US", {
+    month: "long",
+    day: "numeric",
+    year: "numeric",
+  });
+}
+
+/**
+ * Options for relative date formatting.
+ */
+export interface FormatRelativeDateOptions {
+  /**
+   * Reference date to compare against. Defaults to current date.
+   */
+  now?: Date;
+}
+
+/**
+ * Format a date as a relative time string.
+ * @example
+ * formatRelativeDate("2024-01-15") // "Today" (if today is Jan 15)
+ * formatRelativeDate("2024-01-14") // "Yesterday" (if today is Jan 15)
+ * formatRelativeDate("2024-01-10") // "5 days ago" (if today is Jan 15)
+ * formatRelativeDate("2024-01-01") // "2 weeks ago" (if today is Jan 15)
+ * formatRelativeDate("2023-06-15") // "Jun 15, 2023" (older dates)
+ */
+export function formatRelativeDate(
+  date: DateInput,
+  options?: FormatRelativeDateOptions,
+): string {
+  const d = toDate(date);
+  const now = options?.now ?? new Date();
+  const diffDays = daysDiff(d, now);
+
+  if (diffDays === 0) {
+    return "Today";
+  }
+  if (diffDays === 1) {
+    return "Yesterday";
+  }
+  if (diffDays < 7) {
+    return `${String(diffDays)} days ago`;
+  }
+  if (diffDays < 30) {
+    const weeks = Math.floor(diffDays / 7);
+    return weeks === 1 ? "1 week ago" : `${String(weeks)} weeks ago`;
+  }
+
+  // For older dates, show the actual date
+  return d.toLocaleDateString("en-US", {
+    month: "short",
+    day: "numeric",
+    year: d.getFullYear() !== now.getFullYear() ? "numeric" : undefined,
+  });
+}
+
+/**
+ * Format a date as a relative time string, with "Never" for null values.
+ * Useful for displaying "last used" timestamps.
+ * @example
+ * formatRelativeTime("2024-01-15") // "Today"
+ * formatRelativeTime(null) // "Never"
+ */
+export function formatRelativeTime(
+  date: DateInput | null | undefined,
+  options?: FormatRelativeDateOptions,
+): string {
+  if (date === null || date === undefined) {
+    return "Never";
+  }
+  return formatRelativeDate(date, options);
+}