Message separator currently displays date instead of “Today” for current day messages

Description

In the chat message list, the date separator currently displays the full formatted date even for messages sent on the current day.

Example: MAY 17, 2026
Instead, it should display a more user-friendly label such as: Today

Current Behavior

The MessageSeparator component always formats the separator using:

t('message_separator_date', {
  val: new Date(date),
  formatParams: {
    val: {
      month: 'short',
      day: '2-digit',
      year: 'numeric',
    },
  },
})

As a result, today's messages also show the full date.

Expected Behavior

Current day messages should display: Today
Previous day messages can optionally display: Yesterday
Older messages should continue displaying formatted dates.

Suggested Fix

Update the MessageSeparator component to check whether the message date belongs to the current day before formatting the date.

before applying the default date formatter.

Example:
if (isToday(date)) return t('today');
if (isYesterday(date)) return t('yesterday');

Benefits

• Improves readability and UX
• Matches common chat application behavior (WhatsApp, Slack, Discord, etc.)
• Makes recent conversations easier to understand quickly

Affected Component

MessageSeparator

Start by locating the MessageSeparator component and reading the date-formatting call described in the issue. Verify how current, previous, and older message dates are rendered; done means current-day messages show “Today” while older messages retain the expected date format.