fix(tournaments): load both user bots and official bots in join dialog

openJoinDialog now fetches user bots and official bots in parallel via
forkJoin. Each section shows its own empty state independently.

Official bot difficulty buttons are hidden when no official bots are
registered. User bots empty state links to /bots to create one.

Disables all join buttons while any join is in progress.

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

src/app/pages/tournaments/tournaments.component.ts

@@ -3,6 +3,7 @@ import { CommonModule, TitleCasePipe } from '@angular/common';
 import { Router, RouterLink } from '@angular/router';
 import { FormBuilder, FormGroup, FormsModule, ReactiveFormsModule, Validators } from '@angular/forms';
 import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
+import { forkJoin } from 'rxjs';
 import { TournamentService } from '../../services/tournament.service';
 import { AuthService } from '../../services/auth.service';
 import { BotService } from '../../services/bot.service';
@@ -58,6 +59,7 @@ export class TournamentsComponent implements OnInit {
 
   joinDialogTournamentId: string | null = null;
   userBots: Bot[] = [];
+  officialBots: Bot[] = [];
   botsLoading = false;
   joiningBotId: string | null = null;
   joinError: string | null = null;
@@ -175,16 +177,22 @@ export class TournamentsComponent implements OnInit {
     this.joinDialogTournamentId = tournamentId;
     this.joinError = null;
     this.botsLoading = true;
-    this.botService.listOfficial()
+    forkJoin({ user: this.botService.list(), official: this.botService.listOfficial() })
       .pipe(takeUntilDestroyed(this.destroyRef))
       .subscribe({
-        next: bots => { this.userBots = bots; this.botsLoading = false; },
+        next: ({ user, official }) => {
+          this.userBots = user;
+          this.officialBots = official;
+          this.botsLoading = false;
+        },
         error: () => { this.botsLoading = false; }
       });
   }
 
   closeJoinDialog(): void {
     this.joinDialogTournamentId = null;
+    this.userBots = [];
+    this.officialBots = [];
     this.joiningBotId = null;
     this.joinError = null;
     this.joiningOfficialDifficulty = null;