Implement PlaceholderHelp component across various forms for enhanced user guidance

- Integrated PlaceholderHelp component into multiple forms including WelcomeForm, TagsManager, and StatsForm to provide contextual hints for available placeholders.
- Updated DiscordEmbedBuilder to support placeholder presets, improving user experience when creating embeds.
- Enhanced localization files to include new placeholder descriptions, ensuring clarity in both English and German.
- Refactored related components to maintain consistency in placeholder handling across the application.

packages/shared/src/phase2.test.ts

@@ -17,6 +17,16 @@ describe('phase2 helpers', () => {
     expect(result).toBe('Hello <@1> on Nexumi');
   });
 
+  it('expands bracket channel mentions', () => {
+    const result = applyWelcomePlaceholders('Join ["123456789012345678"] please', {});
+    expect(result).toBe('Join <#123456789012345678> please');
+  });
+
+  it('keeps native discord channel mentions', () => {
+    const result = applyWelcomePlaceholders('Join <#123456789012345678> please', {});
+    expect(result).toBe('Join <#123456789012345678> please');
+  });
+
   it('detects discord invites', () => {
     expect(isDiscordInvite('join https://discord.gg/test')).toBe(true);
     expect(isDiscordInvite('hello world')).toBe(false);

packages/shared/src/phase2.ts

@@ -162,14 +162,23 @@ export const WELCOME_PLACEHOLDERS = [
   '{memberCount}'
 ] as const;
 
+/**
+ * Expands dashboard-friendly channel mentions `["123…"]` into Discord's
+ * native `<#123…>` mention format. Raw `<#id>` mentions are left untouched.
+ */
+export function expandBracketChannelMentions(template: string): string {
+  return template.replace(/\["(\d{17,20})"\]/g, '<#$1>');
+}
+
 export function applyWelcomePlaceholders(
   template: string,
   vars: Record<string, string | number>
 ): string {
-  return Object.entries(vars).reduce(
+  const withVars = Object.entries(vars).reduce(
     (acc, [name, value]) => acc.replaceAll(`{${name}}`, String(value)),
     template
   );
+  return expandBracketChannelMentions(withVars);
 }
 
 export function countEmojis(content: string): number {

packages/shared/src/phase4.ts

@@ -38,14 +38,17 @@ export const SuggestionStatusSchema = z.enum([
 ]);
 export type SuggestionStatus = z.infer<typeof SuggestionStatusSchema>;
 
+import { expandBracketChannelMentions } from './phase2.js';
+
 export function applyTagPlaceholders(
   template: string,
   vars: Record<string, string>
 ): string {
-  return Object.entries(vars).reduce(
+  const withVars = Object.entries(vars).reduce(
     (acc, [key, value]) => acc.replaceAll(`{${key}}`, value),
     template
   );
+  return expandBracketChannelMentions(withVars);
 }
 
 export function pickRandomWinners<T>(items: T[], count: number): T[] {