fix(process): retain child scope and bound native exit waits (#5280)

Retain original parent/child scope and prior native-generation proof across exit settlement and token retries. Keep historical scope separate from signal authority, count each supplied snapshot once, and share one existing native-exit deadline throughout cleanup.

Validated 387 affected tests (one Darwin-only skip), five controls repeated three times, and 30 synced-main integration tests (one platform skip). Synced-head static, architecture, docs and discovery checks pass; real GDB qualification passes 44 CLI/MCP cases. Native-observer edge controls are simulated.

Assisted-by: Reimu (gensokyo-skills:reimu-incident-triage)

Assisted-by: Kogasa (gensokyo-skills:kogasa-surprise-testing)

src/process/ProcessLifecycle.ts

@@ -10,6 +10,11 @@ export type ProcessLifecycleObservation =
 export const PROCESS_CLEANUP_VERIFICATION_GRACE_MS = 1_000;
 export const PROCESS_CLEANUP_VERIFICATION_INTERVAL_MS = 25;
 
+/** One operation owns a lazily started native-exit waiting window. */
+export interface ProcessExitSettlementBudget {
+  deadline: number | undefined;
+}
+
 export const processIdentityHasExited = (
   identity: ProcessIdentityObservation | undefined,
 ): boolean =>