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/entities/timedexecute-config.entity.ts

@@ -0,0 +1,33 @@
+import { Entity, PrimaryGeneratedColumn, Column, ManyToOne, JoinColumn } from 'typeorm';
+import { License } from './license.entity';
+
+@Entity('timedexecute_configs')
+export class TimedExecuteConfig {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column({ type: 'uuid' })
+  license_id: string;
+
+  @Column({ type: 'varchar', length: 100 })
+  config_name: string;
+
+  @Column({ type: 'text', nullable: true })
+  description: string | null;
+
+  @Column({ type: 'jsonb', default: () => "'{}'" })
+  config_data: Record<string, any>;
+
+  @Column({ type: 'boolean', default: false })
+  is_active: boolean;
+
+  @Column({ type: 'timestamptz', default: () => 'NOW()' })
+  created_at: Date;
+
+  @Column({ type: 'timestamptz', default: () => 'NOW()' })
+  updated_at: Date;
+
+  @ManyToOne(() => License, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'license_id' })
+  license: License;
+}