feat: add settings page with guild config, game settings, and command toggles

Implements the full admin settings page covering all game settings
(leveling, economy, inventory, lootdrops, trivia, moderation, commands)
and guild settings (roles, channels, welcome message, moderation,
feature overrides). Includes role/channel pickers, trivia category
multi-select, and a feature override flag editor.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/src/routes/settings.routes.ts

@@ -139,7 +139,7 @@ async function handler(ctx: RouteContext): Promise<Response | null> {
                     return a.name.localeCompare(b.name);
                 });
 
-            return jsonResponse({ roles, channels, commands });
+            return jsonResponse({ guildId: env.DISCORD_GUILD_ID, roles, channels, commands });
         }, "fetch settings meta");
     }