Refactor database SSL configuration for improved clarity and flexibility

- Updated SSL settings in database.module.ts and ormconfig.ts to use DATABASE_SSL environment variable for better control over SSL usage.
- Clarified comments to indicate that SSL is only necessary for remote PostgreSQL instances, enhancing understanding for local development setups.

backend/src/database/database.module.ts

@@ -37,12 +37,11 @@ import { Unique } from './validators/unique.validator';
           query_timeout: 30_000,
           statement_timeout: 30_000,
         },
-        // No SSL for local/Docker environments
-        ssl:
-          configService.get('ENVIRONMENT') === 'local' ||
-          configService.get('ENVIRONMENT') === 'development'
-            ? false
-            : { rejectUnauthorized: false },
+        // SSL is only needed for remote/managed PostgreSQL (e.g. AWS RDS).
+        // Self-hosted Docker setups use an internal network — no SSL required.
+        ssl: configService.get('DATABASE_SSL') === 'true'
+          ? { rejectUnauthorized: false }
+          : false,
       }),
     }),
   ],