Add PostgreSQL-backed data storage support (#444)

Co-authored-by: samanhappy <samanhappy@gmail.com>

src/db/entities/SystemConfig.ts

@@ -0,0 +1,43 @@
+import { Entity, Column, PrimaryColumn, CreateDateColumn, UpdateDateColumn } from 'typeorm';
+
+/**
+ * System configuration entity for database storage
+ * Using singleton pattern - only one record with id = 'default'
+ */
+@Entity({ name: 'system_config' })
+export class SystemConfig {
+  @PrimaryColumn({ type: 'varchar', length: 50, default: 'default' })
+  id: string;
+
+  @Column({ type: 'simple-json', nullable: true })
+  routing?: Record<string, any>;
+
+  @Column({ type: 'simple-json', nullable: true })
+  install?: Record<string, any>;
+
+  @Column({ type: 'simple-json', nullable: true })
+  smartRouting?: Record<string, any>;
+
+  @Column({ type: 'simple-json', nullable: true })
+  mcpRouter?: Record<string, any>;
+
+  @Column({ type: 'varchar', length: 10, nullable: true })
+  nameSeparator?: string;
+
+  @Column({ type: 'simple-json', nullable: true })
+  oauth?: Record<string, any>;
+
+  @Column({ type: 'simple-json', nullable: true })
+  oauthServer?: Record<string, any>;
+
+  @Column({ type: 'boolean', nullable: true })
+  enableSessionRebuild?: boolean;
+
+  @CreateDateColumn({ name: 'created_at', type: 'timestamp' })
+  createdAt: Date;
+
+  @UpdateDateColumn({ name: 'updated_at', type: 'timestamp' })
+  updatedAt: Date;
+}
+
+export default SystemConfig;