fix: add missing reasonSuffix declaration in stopAuto

The reason parameter was added to stopAuto() but the reasonSuffix
variable derived from it was never declared, causing TS2304 errors.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/auto.ts

@@ -567,6 +567,7 @@ function startDispatchGapWatchdog(ctx: ExtensionContext, pi: ExtensionAPI): void
 
 export async function stopAuto(ctx?: ExtensionContext, pi?: ExtensionAPI, reason?: string): Promise<void> {
   if (!active && !paused) return;
+  const reasonSuffix = reason ? ` — ${reason}` : "";
   clearUnitTimeout();
   if (lockBase()) clearLock(lockBase());
   clearSkillSnapshot();