fix(migrations): PostgreSQL compatibility; add pg dependency

apps/backend/.env.example

@@ -1,4 +1,8 @@
 # Database Configuration
+# When DATABASE_URL is set, PostgreSQL will be used automatically.
+# Otherwise the backend falls back to local SQLite using DATABASE_PATH.
+DATABASE_URL=postgresql://vaultix_user:vaultix_password@localhost:5432/vaultix_db
+DATABASE_SSL=false
 DATABASE_PATH=./data/vaultix.db
 
 # JWT Configuration

apps/backend/package.json

@@ -54,6 +54,7 @@
     "rxjs": "^7.8.1",
     "socket.io": "^4.8.3",
     "sqlite3": "^5.1.7",
+    "pg": "^8.11.0",
     "stellar-sdk": "^13.3.0",
     "swagger-ui-express": "^5.0.1",
     "typeorm": "^0.3.28"

apps/backend/src/app.controller.ts

@@ -1,12 +1,48 @@
 import { Controller, Get } from '@nestjs/common';
+import { InjectDataSource } from '@nestjs/typeorm';
+import { DataSource } from 'typeorm';
 import { AppService } from './app.service';
 
 @Controller()
 export class AppController {
-  constructor(private readonly appService: AppService) {}
+  constructor(
+    private readonly appService: AppService,
+    @InjectDataSource()
+    private readonly dataSource: DataSource,
+  ) {}
 
   @Get()
   getHello(): string {
     return this.appService.getHello();
   }
+
+  @Get('health/database')
+  async getDatabaseHealth() {
+    const dbType = this.dataSource.options.type;
+    const isConnected = this.dataSource.isInitialized;
+    let migrationCount = 0;
+    let migrationStatus = 'unknown';
+
+    try {
+      await this.dataSource.query('SELECT 1');
+      const result = await this.dataSource.query(
+        'SELECT COUNT(*) as count FROM "migrations"',
+      );
+      const countValue = Array.isArray(result) ? result[0]?.count : undefined;
+      migrationCount = typeof countValue === 'string' ? Number(countValue) : Number(countValue || 0);
+      migrationStatus = Number.isFinite(migrationCount) ? 'ok' : 'unknown';
+    } catch (error) {
+      migrationStatus = 'unavailable';
+    }
+
+    return {
+      status: isConnected ? 'ok' : 'down',
+      database: {
+        type: dbType,
+        connected: isConnected,
+        migrationStatus,
+        migrationsExecuted: migrationCount,
+      },
+    };
+  }
 }