fix: resolve type errors in process-lost-reaper PR

- Fix malformed try/catch/finally blocks in heartbeat executeRun
- Declare activeRunExecutions Set to track in-flight runs
- Add resumeQueuedRuns function and export from heartbeat service
- Add initdbFlags to EmbeddedPostgresCtor type

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/index.ts

@@ -53,6 +53,7 @@ type EmbeddedPostgresCtor = new (opts: {
   password: string;
   port: number;
   persistent: boolean;
+  initdbFlags?: string[];
   onLog?: (message: unknown) => void;
   onError?: (message: unknown) => void;
 }) => EmbeddedPostgresInstance;