Reuse the health check's temp dir instead of orphaning it

check_posters unconditionally re-made WORKDIR, so when check_unmatched had
already created one the first was left behind — cleanup only removes the last.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

plex/bin/plex-health

@@ -203,7 +203,9 @@ check_posters() {
   local sections
   sections="$(plex_get /library/sections)"
   local key title type code bad total
-  WORKDIR="$(mktemp -d)"
+  # Reuse the dir check_unmatched may already have made; overwriting WORKDIR
+  # here would orphan it, since cleanup only removes the last one.
+  [[ -n "$WORKDIR" ]] || WORKDIR="$(mktemp -d)"
   while IFS=$'\t' read -r key title type; do
     case "$type" in
       movie) code=1 ;;