fix: Conflict agent auto-dismiss fails on page load/remount

prevStateRef was initialized with current state, so when the page loaded
with an already-idle conflict agent, the transition guard was immediately
false and dismiss() never fired. Initialize with null instead.

apps/web/src/components/review/ConflictResolutionPanel.tsx

@@ -13,7 +13,7 @@ interface ConflictResolutionPanelProps {
 export function ConflictResolutionPanel({ initiativeId, conflicts, onResolved }: ConflictResolutionPanelProps) {
   const { state, agent, questions, spawn, resume, stop, dismiss } = useConflictAgent(initiativeId);
   const [showManual, setShowManual] = useState(false);
-  const prevStateRef = useRef(state);
+  const prevStateRef = useRef<string | null>(null);
 
   // Auto-dismiss and re-check mergeability when conflict agent completes
   useEffect(() => {