Add Emby/Jellyfin deep API health checks to docker_watchdog.sh

Both had a basic HTTP check (Emby) or no coverage at all (Jellyfin), but
neither would have caught today's real incident: Jellyfin's SQLite
database locked up hard (repeated 'database table is locked' errors,
30s+ query timeouts) while its own /System/Info endpoint kept responding
200 the whole time — a basic HTTP check on that endpoint would never have
tripped. /Users forces an actual DB round-trip and was confirmed live to
hang during the exact incident.

Generalized the API check's success condition to also accept array-shaped
responses (/Users returns an array; the existing check only recognized
object fields like .ServerName/.Id/.Version, which would error when
applied to an array) — benefits any future array-returning endpoint, not
just this one. Also corrected the host.conf.template's API_CHECKS format
comment, which described a 3-field format the code never actually used.

Watchdogs/docker_watchdog.sh

@@ -899,7 +899,10 @@ CYCLE_START=$(date +%s)
                 continue
             fi
 
-            if echo "$_resp" | jq -e '.ServerName // .Id // .Version' >/dev/null 2>&1; then
+            # Object-shaped responses (e.g. /System/Info) pass via ServerName/Id/Version.
+            # Array-shaped responses (e.g. /Users) pass on any valid array — indexing an
+            # array with a string key would itself error in jq, so branch on type first.
+            if echo "$_resp" | jq -e 'if type == "array" then true else (.ServerName // .Id // .Version) != null end' >/dev/null 2>&1; then
                 set_strikes "${container}_api" 0 "$WATCHDOG_STATE_FILE"
             else
                 API_STRIKES=$(get_strikes "${container}_api" "$WATCHDOG_STATE_FILE")