The default workspace lives at STATE_DIR/workspace, so denying STATE_DIR itself
403'd legitimate workspace media. STATE_DIR is already in _hermes_roots, so its
sensitive subdirs (STATE_DIR/sessions, /memories, /profiles, etc.) are still
covered by the per-root subdir loop; direct sensitive files are still caught by
the filename denies. Drop the wholesale _state_dir deny. Adds a regression test
proving STATE_DIR/workspace/shot.png serves while STATE_DIR/sessions/*.json 403s.