feat: web dashboard and playground work

The NexusDashboard-parity dashboard (dDashboardServer) and everything built on it on the experimental branch:
accounts, characters, properties and moderation tools, permissions shared with in-game slash commands, economy
reports, World 3D and property 3D views with client scenery, scheduled events (features, vanity changes, live
events, announcements, restarts), vanity files and events, the CDClient browser, the message inspector with saved
captures, chat filter tools, community challenges, live ops, the AI moderator helper, and the server-side changes
they need.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dNet/MailInfo.h

@@ -20,6 +20,8 @@ struct MailInfo {
 	uint64_t timeSent{};
 	bool wasRead{};
 	uint16_t languageCode{};
+	// Attachment item config (LDF "key=type:value" lines), kept so items keep their data through the mail
+	std::string itemConfig;
 	struct {
 		LWOOBJID itemID{};
 		int16_t itemCount{};