feat(stateprocess): add managed state processes with lifecycle controls, scheduled actions, and disposal safety

ts/smartstate.classes.computed.ts

@@ -1,5 +1,5 @@
 import * as plugins from './smartstate.plugins.js';
-import { combineLatest, map } from 'rxjs';
+import { combineLatest, map, distinctUntilChanged } from 'rxjs';
 import type { StatePart } from './smartstate.classes.statepart.js';
 
 /**
@@ -12,5 +12,6 @@ export function computed<TResult>(
 ): plugins.smartrx.rxjs.Observable<TResult> {
   return combineLatest(sources.map((sp) => sp.select())).pipe(
     map((states) => computeFn(...states)),
+    distinctUntilChanged((a, b) => JSON.stringify(a) === JSON.stringify(b)),
   ) as plugins.smartrx.rxjs.Observable<TResult>;
 }