hermes update only cleared .update_check for the active HERMES_HOME,
leaving other profiles showing stale 'N commits behind' in their banner.
Now _invalidate_update_cache() iterates over ~/.hermes/ (default) plus
every directory under ~/.hermes/profiles/ to clear all caches. The git
repo is shared across profiles so a single update brings them all current.
Reported by SteveSkedasticity on Discord.
- Add background thread mechanism (prefetch_update_check/get_update_result)
so git fetch runs in parallel with skill sync and agent init
- Fix repo path fallback in check_for_updates() for dev installs
- Remove duplicate build_welcome_banner (~180 lines) and
_format_context_length from cli.py — the banner.py version is
now the single source of truth
- Port skin banner_hero/banner_logo support and terminal width check
from cli.py's version into banner.py
- Add update status output to hermes version command
- Add unit tests for update check, prefetch, and version string
