Refactor embed handling and enhance user experience across components

- Integrated the new `buildEmbedFromPayload` function in Scheduler, Tags, and Welcome components to streamline embed creation and management.
- Updated validation schemas to require embed content checks, ensuring robust data integrity for embeds.
- Enhanced localization files to include new placeholder descriptions and improve user guidance for embed fields.
- Refactored embed parsing logic to utilize the `WelcomeEmbedSchema`, improving consistency and validation across the application.

apps/bot/src/modules/welcome/service.ts

@@ -19,8 +19,10 @@ export function buildPlaceholderVars(member: GuildMember, guild: Guild) {
     'user.name': member.displayName,
     'user.tag': member.user.tag,
     'user.id': member.id,
+    'user.avatar': member.user.displayAvatarURL({ size: 256 }),
     server: guild.name,
-    memberCount: guild.memberCount
+    memberCount: guild.memberCount,
+    'server.icon': guild.iconURL({ size: 128 }) ?? ''
   };
 }