This commit also fixes of other potential issues and improves logging.
Adds two unofficial env variables so advanced users can experiment: 1. PHOTOPRISM_FACE_KIDS_DIST=0.6950 (range: 0.1-1.5, -1 to disable) 2. PHOTOPRISM_FACE_IGNORE_DIST=0.86 (range: 0.1-1.5, -1 to disable)