feat: Add BetterChat + TimedExecute plugin config modules

- DB migrations 017 (betterchat_configs) and 020 (timedexecute_configs) applied
- TypeORM entities matching production schema exactly
- NestJS modules with full CRUD + apply-to-server + import-from-server
- Pinia stores following teleport config pattern
- BetterChatView: Chat Groups editor with color pickers, font sizes, format strings; Settings tab with word filter, anti-flood, player tagging
- TimedExecuteView: TimerRepeat with presets, RealTime-Timer, OnConnect/OnDisconnect command lists
- Wired into app.module.ts, router, DashboardLayout nav

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

backend-nest/src/modules/betterchat/dto/create-betterchat-config.dto.ts

@@ -0,0 +1,19 @@
+import { IsString, IsOptional, IsObject, MaxLength } from 'class-validator';
+import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
+
+export class CreateBetterChatConfigDto {
+  @ApiProperty({ example: 'Default Chat Config' })
+  @IsString()
+  @MaxLength(100)
+  config_name: string;
+
+  @ApiPropertyOptional({ example: 'Standard BetterChat settings' })
+  @IsString()
+  @IsOptional()
+  description?: string;
+
+  @ApiPropertyOptional()
+  @IsObject()
+  @IsOptional()
+  config_data?: Record<string, any>;
+}