Add Sonarr discovery; wire search commands to all arr adds

- New: Media/playback_aware_sonarr_discovery.sh — two-stage TV show
  discovery using Emby episode play history → TMDB TV recommendations.
  Multi-user aware: diversity score (0-50) is primary seed driver so one
  user binge-watching alone cannot dominate. Per-user episode cap (default 8)
  limits single-user volume contribution. TMDB→TVDB via external_ids for
  reliable Sonarr lookup. monitor=future by default.

- Add to WEEKLY_MAINTENANCE_SCRIPTS; Sonarr discovery config block in
  master.conf (threshold=52, lookback=14d, max_adds=3, user_ep_cap=8).

- Fix: all arr add scripts were not triggering searches after adding.
  Added _radarr_command/_lidarr_command/_sonarr_command helpers and fire
  MoviesSearch/ArtistSearch/SeriesSearch immediately after each successful
  add. Affects: playback_aware_radarr_discovery.sh, emby_to_lidarr_sync.sh,
  emby_to_radarr_sync.sh, emby_to_sonarr_sync.sh.

Tools/emby_to_lidarr_sync.sh

@@ -102,6 +102,14 @@ _lidarr_post() {
         "${LIDARR_URL}/api/v1/artist" 2>/dev/null
 }
 
+_lidarr_command() {
+    curl -sf --max-time 20 -X POST \
+        -H "X-Api-Key: $LIDARR_API_KEY" \
+        -H "Content-Type: application/json" \
+        -d "$1" \
+        "${LIDARR_URL}/api/v1/command" 2>/dev/null
+}
+
 _is_placeholder_artist() {
     local a="${1,,}"
     [[ "$a" =~ ^(va|various|various artists|unknown artist|unknown|soundtrack|original soundtrack|ost)$ ]]
@@ -267,6 +275,8 @@ for artist in "${MISSING[@]}"; do
     RESULT=$(_lidarr_post "$PAYLOAD")
 
     if echo "$RESULT" | jq -e '.id' >/dev/null 2>&1; then
+        ARTIST_ID=$(echo "$RESULT" | jq -r '.id')
+        _lidarr_command "{\"name\":\"ArtistSearch\",\"artistId\":${ARTIST_ID}}" >/dev/null
         log "  $ICON_DONE Added: $LIDARR_NAME"
         (( ADDED++ ))
     else