feat(companion): add waitForIdle runtime drain helper

src/companion/platformClients.ts

@@ -22,6 +22,7 @@ import type {
   SetNodeLocationInput,
   SystemCapabilitiesResult,
   SystemNodesResult,
+  WaitForIdleOptions,
 } from './runtimeClient.js';
 import {
   CompanionHeartbeatLoop,
@@ -325,6 +326,10 @@ export class MacOSCompanionClient {
     return this.runtime.waitForContextWarning(options);
   }
 
+  waitForIdle(options?: WaitForIdleOptions): Promise<void> {
+    return this.runtime.waitForIdle(options);
+  }
+
   private resolveSessionId(sessionId?: string): string {
     const resolved = sessionId ?? this.defaultSessionId;
     if (!resolved) {
@@ -579,6 +584,10 @@ export class IOSCompanionClient {
     return this.runtime.waitForContextWarning(options);
   }
 
+  waitForIdle(options?: WaitForIdleOptions): Promise<void> {
+    return this.runtime.waitForIdle(options);
+  }
+
   private resolveSessionId(sessionId?: string): string {
     const resolved = sessionId ?? this.defaultSessionId;
     if (!resolved) {
@@ -831,6 +840,10 @@ export class AndroidCompanionClient {
     return this.runtime.waitForContextWarning(options);
   }
 
+  waitForIdle(options?: WaitForIdleOptions): Promise<void> {
+    return this.runtime.waitForIdle(options);
+  }
+
   private resolveSessionId(sessionId?: string): string {
     const resolved = sessionId ?? this.defaultSessionId;
     if (!resolved) {