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

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

packages/app/src/i18n/resources/en.ts

@@ -774,6 +774,8 @@ export const en = {
         closeChangesTab: "Close Changes tab",
         binaryFile: "Binary file",
         tooLarge: "Diff too large to display",
+        previewTooLargeTitle: "This diff is too large to preview",
+        previewTooLargeDescription: "Narrow the comparison to preview it here",
         unified: "Unified diff",
         split: "Side-by-side diff",
         switchToUnified: "Switch to unified diff",