formatConsoleTimestamp previously used Date.toISOString() which always
returns UTC time (suffixed with Z). This confused users whose local
timezone differs from UTC.
Now uses local time methods (getHours, getMinutes, etc.) and appends the
local UTC offset (e.g. +08:00) instead of Z. The pretty style returns
local HH:MM:SS. The hasTimestampPrefix regex is updated to accept both
Z and +/-HH:MM offset suffixes.
Closes#14699
