On Windows (fr-FR, es-AR, de-DE reports) the zone name arrives in the ANSI
code page but is decoded under a UTF-8 LC_CTYPE (UTF-8 mode, or Piper/espeak
flipping the process locale mid-run) with surrogateescape. datetime.strftime
splices tzname() in as UTF-8, so "%Z" raised UnicodeEncodeError while the
system prompt was being built and every new/compressed conversation died.
Rework safe_strftime into a small repair: output is untouched for valid text
(the system prompt stays byte-identical), surrogateescape'd bytes decode back
through the ANSI code page ("heure d'été"), anything else degrades to U+FFFD,
and a raising "%Z" is rendered from the repaired tzname(). hermes_time no
longer imports agent.* at module load.
Route the remaining locale-name sites through it: cron quota-hold notice,
auxiliary cooldown notice, cron session titles, session_search dates,
insights, learning graph and billing renew dates. Tests use real datetimes
with a surrogate zone name instead of stubbed strftime.
Fixes#102910
Co-authored-by: Aniruddha Adak <127435065+aniruddhaadak80@users.noreply.github.com>