fix: use custom event for training panel toggle, no more poll inference

SkillInsertDialog dispatches SKILL_TOGGLED_EVENT on user click.
AssistantWorkspace listens for that event to set applied state.
Completely eliminates poll-based state inference that caused flash.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/app/lib/use-training-mode.ts

@@ -3,6 +3,7 @@
 import { useCallback, useEffect, useState } from "react";
 
 export const SESSION_UPDATED_EVENT = "claw-session-updated";
+export const SKILL_TOGGLED_EVENT = "claw-skill-toggled";
 const APPLIED_STORAGE_PREFIX = "claw.training.applied:";
 
 const MODEL_ITERATION_SKILL_NAMES = new Set(["model-iteration"]);
@@ -158,6 +159,15 @@ export function dispatchSessionUpdated(detail: SessionUpdatedDetail) {
 	);
 }
 
+export type SkillToggledDetail = { skill: string; enabled: boolean };
+
+export function dispatchSkillToggled(detail: SkillToggledDetail) {
+	if (typeof window === "undefined") return;
+	window.dispatchEvent(
+		new CustomEvent<SkillToggledDetail>(SKILL_TOGGLED_EVENT, { detail }),
+	);
+}
+
 export function useTrainingMode(sessionId: string | null) {
 	const [isTraining, setIsTraining] = useState(false);
 	const [loaded, setLoaded] = useState(false);