bug: "Last login" shows ambiguous weekday with no date for logins older than today

Description

In the User Information panel, the Last login field uses formatTimestamp (packages/react/src/lib/formatTimestamp.js), which renders any timestamp that isn't from today as just a weekday + time, with no date:

return isDifferentDay
  ? `${date.toLocaleDateString('en-US', { weekday: 'long' })} ${formattedTime}`
  : formattedTime;

isDifferentDay is only "not today", so every past login collapses to a bare weekday. A login from 3 months ago — or even over a year ago — shows the same kind of string as one from last week, with no way to tell them apart.

Steps to reproduce

1. Open the User Information panel for a user whose last login was more than a few days ago.
2. Look at the Last login field.

Actual behavior

The field shows only a weekday and time, e.g.:

login 90 days ago : "Tuesday 10:49 PM"   (actual: Tue Mar 03 2026)
login 400 days ago: "Sunday 10:49 PM"    (actual: Apr 27 2025 — over a year ago)

A 14-month-old login is indistinguishable from a recent one, and no year is ever shown.

Expected behavior

For timestamps that aren't from today, show an unambiguous date (with year), e.g. "Mar 3, 2026, 10:49 PM".

Notes

The codebase already does this correctly elsewhere — the adjacent created at field uses formatTimestampGetDate ("March 5, 2026"), and Message.js formats dates via date-fns format(date, 'MMMM d, yyyy'). So this is an inconsistency in formatTimestamp specifically.

I found this while reading the date-formatting helpers and would like to work on it.

File: packages/react/src/lib/formatTimestamp.js

Start with packages/react/src/lib/formatTimestamp.js and compare its non-today branch with formatTimestampGetDate and the date formatting used in Message.js. Update the Last login output so older timestamps include an unambiguous date and year, then verify the User Information panel examples match the expected format.