fix: reject oversized checkout diffs (#2488)

* fix: reject oversized checkout diffs

* fix(diff): keep large previews from disconnecting clients

The physical socket limit is an OOM backstop, not a frame-size contract. Bound structured diff construction incrementally and report oversized previews without closing the client's socket.

* fix(app): preserve oversized diff state

* fix(diff): stay within relay frame limit

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/git/use-working-diff.ts

@@ -79,6 +79,7 @@ export function useWorkingDiff({
   const {
     files,
     payloadError: diffPayloadError,
+    diffTooLarge,
     isLoading: isDiffLoading,
   } = useCheckoutDiffQuery({
     serverId,
@@ -123,6 +124,7 @@ export function useWorkingDiff({
     selectBase,
     files,
     diffPayloadError,
+    diffTooLarge,
     isDiffLoading,
     reviewActions,
     reviewAttachment,