fix(relay): expect missing:false on index blob maxBuffer overflow

readBlobAtIndex now returns a missing flag so staged deletions are
distinct from size-capped binary reads; update the overflow test.

src/relay/git-handler-blob-readers.test.ts

@@ -44,6 +44,7 @@ describe('git blob readers', () => {
 
     const result = await readBlobAtIndex(gitBuffer, '/repo', 'large.log')
 
-    expect(result).toEqual({ content: '', isBinary: true })
+    // Why: overflow is size-capped content, not a staged deletion (missing: false).
+    expect(result).toEqual({ content: '', isBinary: true, missing: false })
   })
 })