fix(web): Dismiss button on refine agent ChangeSetBanner now works

The dismiss mutation only invalidated `listAgents` but the hook reads
from `getActiveRefineAgent`, so the banner stayed visible after dismiss.
Added optimistic cache clearing and invalidation for `getActiveRefineAgent`.

packages/web/src/hooks/useRefineAgent.ts

@@ -170,26 +170,34 @@ export function useRefineAgent(initiativeId: string): UseRefineAgentResult {
     onMutate: async ({ id }) => {
       // Cancel outgoing refetches
       await utils.listAgents.cancel();
+      await utils.getActiveRefineAgent.cancel({ initiativeId });
 
-      // Snapshot previous value
+      // Snapshot previous values
       const previousAgents = utils.listAgents.getData();
+      const previousRefineAgent = utils.getActiveRefineAgent.getData({ initiativeId });
 
       // Optimistically remove the agent from the list
       utils.listAgents.setData(undefined, (old = []) =>
         old.filter(a => a.id !== id)
       );
+      // Optimistically clear the active refine agent so the banner disappears immediately
+      utils.getActiveRefineAgent.setData({ initiativeId }, null);
 
-      return { previousAgents };
+      return { previousAgents, previousRefineAgent };
     },
     onSuccess: () => {},
     onError: (err, variables, context) => {
-      // Revert optimistic update
+      // Revert optimistic updates
       if (context?.previousAgents) {
         utils.listAgents.setData(undefined, context.previousAgents);
       }
+      if (context?.previousRefineAgent !== undefined) {
+        utils.getActiveRefineAgent.setData({ initiativeId }, context.previousRefineAgent);
+      }
     },
     onSettled: () => {
       void utils.listAgents.invalidate();
+      void utils.getActiveRefineAgent.invalidate({ initiativeId });
     },
   });