feat(snmp): add configurable SNMP runtime units with v4.3 migration support

ts/migrations/migration-runner.ts

@@ -3,6 +3,7 @@ import { MigrationV1ToV2 } from './migration-v1-to-v2.ts';
 import { MigrationV3ToV4 } from './migration-v3-to-v4.ts';
 import { MigrationV4_0ToV4_1 } from './migration-v4.0-to-v4.1.ts';
 import { MigrationV4_1ToV4_2 } from './migration-v4.1-to-v4.2.ts';
+import { MigrationV4_2ToV4_3 } from './migration-v4.2-to-v4.3.ts';
 import { logger } from '../logger.ts';
 
 /**
@@ -21,6 +22,7 @@ export class MigrationRunner {
       new MigrationV3ToV4(),
       new MigrationV4_0ToV4_1(),
       new MigrationV4_1ToV4_2(),
+      new MigrationV4_2ToV4_3(),
     ];
 
     // Sort by version order to ensure they run in sequence