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/fr.ts

@@ -794,6 +794,8 @@ export const fr: TranslationResources = {
         closeChangesTab: "Fermer l'onglet Modifications",
         binaryFile: "Fichier binaire",
         tooLarge: "Diff trop grand pour être affiché",
+        previewTooLargeTitle: "Ce diff est trop volumineux pour être prévisualisé",
+        previewTooLargeDescription: "Réduisez la comparaison pour la prévisualiser ici",
         unified: "Différentiel unifié",
         split: "Différent côte à côte",
         switchToUnified: "Passer au diff unifié",