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/README.md

@@ -0,0 +1,134 @@
+# @reviq/common
+
+Shared utilities for all RevIQ applications. This package contains environment-agnostic code that works in browsers, Node.js, Bun, and other JavaScript runtimes.
+
+## Installation
+
+This package is used internally within the monorepo:
+
+```bash
+# Add to your app's package.json
+"dependencies": {
+  "@reviq/common": "workspace:*"
+}
+```
+
+## Date Formatting
+
+Consistent date formatting utilities for displaying dates across the application.
+
+### Functions
+
+#### `formatDate(date)`
+
+Format a date for display in tables and lists.
+
+```typescript
+import { formatDate } from "@reviq/common";
+
+formatDate("2024-01-15"); // "Jan 15, 2024"
+formatDate(new Date());   // "Jan 15, 2024"
+```
+
+#### `formatDateTime(date)`
+
+Format a date with time for detailed views.
+
+```typescript
+import { formatDateTime } from "@reviq/common";
+
+formatDateTime("2024-01-15T15:30:00"); // "Jan 15, 2024, 3:30 PM"
+```
+
+#### `formatLongDate(date)`
+
+Format a date in long form.
+
+```typescript
+import { formatLongDate } from "@reviq/common";
+
+formatLongDate("2024-01-15"); // "January 15, 2024"
+```
+
+#### `formatRelativeDate(date, options?)`
+
+Format a date as a relative time string.
+
+```typescript
+import { formatRelativeDate } from "@reviq/common";
+
+formatRelativeDate("2024-01-15"); // "Today" (if today is Jan 15)
+formatRelativeDate("2024-01-14"); // "Yesterday"
+formatRelativeDate("2024-01-10"); // "5 days ago"
+formatRelativeDate("2024-01-01"); // "2 weeks ago"
+formatRelativeDate("2023-06-15"); // "Jun 15, 2023"
+
+// With custom reference date
+formatRelativeDate("2024-01-10", { now: new Date("2024-01-15") });
+```
+
+#### `formatRelativeTime(date, options?)`
+
+Same as `formatRelativeDate`, but returns "Never" for null/undefined values. Useful for "last used" timestamps.
+
+```typescript
+import { formatRelativeTime } from "@reviq/common";
+
+formatRelativeTime("2024-01-15"); // "Today"
+formatRelativeTime(null);         // "Never"
+formatRelativeTime(undefined);    // "Never"
+```
+
+## User Utilities
+
+Helper functions for working with user data.
+
+### Functions
+
+#### `getUserInitials(user)`
+
+Generate initials from a user's display name or email.
+
+```typescript
+import { getUserInitials } from "@reviq/common";
+
+getUserInitials({ displayName: "John Doe", email: "john@example.com" }); // "JD"
+getUserInitials({ displayName: "John", email: "john@example.com" });     // "JO"
+getUserInitials({ email: "john@example.com" });                          // "JO"
+getUserInitials(null);                                                   // "??"
+```
+
+#### `formatRole(role)`
+
+Format a role string for display (capitalizes first letter).
+
+```typescript
+import { formatRole } from "@reviq/common";
+
+formatRole("admin");  // "Admin"
+formatRole("member"); // "Member"
+formatRole("owner");  // "Owner"
+```
+
+## Development
+
+```bash
+# Run tests
+bun test
+
+# Build
+bun run build
+
+# Type check
+bun run typecheck
+```
+
+## Adding New Utilities
+
+When adding new utilities to this package:
+
+1. Create a new file in `src/` (e.g., `src/my-utility.ts`)
+2. Add comprehensive tests in `src/my-utility.test.ts`
+3. Export from `src/index.ts`
+4. Run `bun test` to verify tests pass
+5. Run `bun run build` to compile