Plugins: server plugins spawn and remove the server's park mods

A dedicated server's park mods could only be spawned from its console, an admin's chat or a vote,
so a server plugin could not bring out the park its game is played in. A new permission,
server.parks, gives a server copy reskate.server.parks(), which lists the park mods set up with
whether each fits the map running now and is spawned (its objects and minutes left), and
reskate.server.park_spawn(name, minutes?) and park_remove(name), which return ok or false and why.

They go through park-mod add and remove, so the park limits, the map check and the chat lines stay
the server's. Their "[parks]" lines are logged "by plugin <id>". A name is a park mod's own (1 to 16
of a-z 0-9 - _) and minutes are 1 to 1440, or none for until removed. Reading the park files is not
part of this: a plugin brings what it needs to know about a park in its own package.

dingosdk_server_plugin_tests spawns and removes a park mod through a plugin and checks what it is
refused; dingosdk_plugin_tests checks the API on a server copy, and that a player's copy and a
plugin without server.parks cannot use it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hs7xxJDf6SDcQUaXnzmtL5

Server/server_plugins.cpp

@@ -80,6 +80,15 @@ class ServerGame final : public Game {
         host_.set_locks(player, locks, "plugin " + std::string(plugin));
         return {};
     }
+    std::vector<ServerPark> server_parks() override {
+        std::vector<ServerPark> result;
+        for (auto &p : host_.park_status()) result.push_back({std::move(p.name), std::move(p.map), p.here, p.spawned, p.objects, p.minutes_left});
+        return result;
+    }
+    std::string spawn_park(std::string_view plugin, std::string_view name, unsigned minutes) override {
+        return host_.plugin_park(plugin, true, name, minutes);
+    }
+    std::string remove_park(std::string_view plugin, std::string_view name) override { return host_.plugin_park(plugin, false, name, 0); }
     // The skaters of the players in the world, as their latest poses put them. The server has
     // no skater of its own, so this is every player's.
     std::vector<PeerSkater> peer_skaters() override {