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_sonarr_sync.sh

@@ -100,6 +100,14 @@ _sonarr_post() {
         "${SONARR_URL}/api/v3/series" 2>/dev/null
 }
 
+_sonarr_command() {
+    curl -sf --max-time 20 -X POST \
+        -H "X-Api-Key: $SONARR_API_KEY" \
+        -H "Content-Type: application/json" \
+        -d "$1" \
+        "${SONARR_URL}/api/v3/command" 2>/dev/null
+}
+
 # Garbage title filter — catches multi-season folder names and bare fansub tags.
 _is_garbage_title() {
     local t="$1"
@@ -283,6 +291,8 @@ for name in "${SORTED_MISSING[@]}"; do
     RESULT=$(_sonarr_post "$PAYLOAD")
 
     if echo "$RESULT" | jq -e '.id' >/dev/null 2>&1; then
+        SERIES_ID=$(echo "$RESULT" | jq -r '.id')
+        _sonarr_command "{\"name\":\"SeriesSearch\",\"seriesId\":${SERIES_ID}}" >/dev/null
         log "  $ICON_DONE Added: $SONARR_TITLE"
         (( ADDED++ ))
     else