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>

migrations/dlu/mysql/46_slash_commands.sql

@@ -0,0 +1,14 @@
+/* The in-game slash commands as the world servers registered them, so the dashboard can list them and change who may
+   use them. The levels themselves are settings (command_level_<name> in server_config). aliases is comma separated. */
+CREATE TABLE IF NOT EXISTS slash_commands (
+    name VARCHAR(64) NOT NULL PRIMARY KEY,
+    aliases TEXT NOT NULL,
+    help TEXT NOT NULL,
+    info TEXT NOT NULL,
+    default_level TINYINT NOT NULL,
+    min_level TINYINT NOT NULL DEFAULT 0,
+    fixed TINYINT NOT NULL DEFAULT 0,
+    client_handled TINYINT NOT NULL DEFAULT 0,
+    note TEXT NOT NULL,
+    dashboard_permission VARCHAR(64) NOT NULL DEFAULT ''
+);