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/components/assistant-ui/thread.tsx

@@ -93,6 +93,7 @@ import {
 } from "@/lib/claw-active-session";
 import { useClawSessionReplay } from "@/lib/claw-session-replay";
 import { cn } from "@/lib/utils";
+import { dispatchSkillToggled } from "@/lib/use-training-mode";
 
 type ComposerInsertEvent = CustomEvent<{ text: string }>;
 
@@ -1800,6 +1801,7 @@ function SkillInsertDialog() {
 				);
 			}
 			setSkills(payload);
+			dispatchSkillToggled({ skill: skill.name, enabled });
 			setStatus(enabled ? `已启用 ${skill.name}` : `已停用 ${skill.name}`);
 		} catch (err) {
 			setSkills(previous);