fix: 调小 snapshots 的范围

src/utils/fileHistory.ts

@@ -51,7 +51,9 @@ export type FileHistoryState = {
   snapshotSequence: number
 }
 
-const MAX_SNAPSHOTS = 100
+// Disabled: file checkpointing causes unbounded memory growth (100 snapshots × full file backups).
+// See heap snapshot analysis — re-enable only after switching to incremental diffs.
+const MAX_SNAPSHOTS = 20
 export type DiffStats =
   | {
       filesChanged?: string[]