Let the media server card show the whole mesh, not just this host

A partner's Emby URL is http://localhost:8096 — true there, meaningless here —
so nobody queries a partner's media server directly. Each host reports its own
over the SSH call remote_arr_cache_writer.sh already makes, which keeps its API
keys on it and costs no extra connection. Local is the default: opening the tab
to check your own server should not first make you read past a partner's.
A partner with no cache is stated as not collected rather than omitted, because
an empty mesh view and a partner that is down look identical otherwise.

Plugin/unraid/Tools/remote_arr_cache_writer.sh

@@ -152,9 +152,11 @@ for host_var in HOST1 HOST2 HOST3 HOST4 HOST5 HOST6 HOST7 HOST8; do
         "php -r \"
             require_once '/usr/local/emhttp/plugins/varaverk/include/arrs.php';
             require_once '/usr/local/emhttp/plugins/varaverk/include/unraid_api.php';
+            require_once '/usr/local/emhttp/plugins/varaverk/include/media.php';
             echo json_encode([
                 'arrs'    => vv_arrs_local_node(),
                 'monitor' => vv_local_host_stats(),
+                'media'   => function_exists('vv_media_server_stats') ? vv_media_server_stats() : [],
             ]);
         \"" 2>/dev/null)
 
@@ -188,6 +190,19 @@ for host_var in HOST1 HOST2 HOST3 HOST4 HOST5 HOST6 HOST7 HOST8; do
         file_put_contents('$MONITOR_CACHE', json_encode(\$d['monitor']));
     " 2>/dev/null
 
+    # Save media server cache. Collected here rather than queried directly because a partner's
+    # Emby URL is http://localhost:8096 — true on that host and meaningless from this one. The
+    # same reason the arrs are collected this way: each host answers about itself, and its API
+    # keys never leave it.
+    #
+    # Absent on a partner running an older build, which is why it is written only when present:
+    # an empty file would read as "no media servers there" rather than "not collected yet".
+    MEDIA_CACHE="$VV_CACHE_DIR/media_remote_${host_id}.json"
+    echo "$RESULT" | php -r "
+        \$d = json_decode(file_get_contents('php://stdin'), true);
+        if (!empty(\$d['media'])) file_put_contents('$MEDIA_CACHE', json_encode(\$d['media']));
+    " 2>/dev/null
+
     CACHED_TYPES=$(echo "$RESULT" | php -r "
         \$d = json_decode(file_get_contents('php://stdin'), true);
         echo implode(', ', array_column(\$d['arrs']['arrs'] ?? [], 'type'));