vision_analyze used Path('./temp_vision_images') — a relative path that
resolved against cwd. Under Docker the image's WORKDIR is /opt/hermes,
which is root-owned and only chmoded a+rX (read + traversal). Since
#5811 landed (run as non-root hermes UID 10000, Apr 12), remote-URL
vision calls fail with PermissionError on mkdir.
Switch to get_hermes_dir('cache/vision', 'temp_vision_images'): resolves
to $HERMES_HOME/cache/vision/ (= /opt/data/cache/vision/ in Docker —
the user-owned volume mount). Existing installs with the old dir keep
using it via the get_hermes_dir back-compat path; no migration needed.
Only site in the codebase that stored runtime files via Path('./...').
Reported via Discord: https://juick.com/i/p/3089079.jpg → Telegram →
gateway → [Errno 13] Permission denied: 'temp_vision_images'.