fix(review): bound E2B readBytes at the seam, prove conditional-registration disposal, and align read_image contracts

- E2BFileSystem.readBytes now short-circuits on the stat size before any
  content transfer and streams the remote object, cancelling at the first
  chunk past the cap, honoring the seam's bounded-buffering contract; the
  fs-e2b README pair documents the new primitive.
- The tool-fs HMR test now proves the attachments-scoped registration:
  disposing the store withdraws read_image while read/write/edit stay,
  remounting restores it, and disposing the plugin withdraws everything.
- read_image caps reads at the smaller of maxImageBytes and
  maxMessageImageBytes, records an absent observation for a missing
  target like its sibling read, widens the mismatch remedy to cover
  out-of-family formats, and renames the gate's parameter to
  requestedPath; module/apply/registration JSDoc now match the shipped
  composition. zh terminology aligned; the examples manifest keeps its
  literal arrow.

packages/e2b/fs-e2b/tests/filesystem.spec.ts

@@ -488,6 +488,22 @@ describe('E2BFileSystem identity, metadata, and reads', () => {
     await expectCode(fs.readBytes(target, undefined, 4), 'FS_ABORTED')
   })
 
+  it('readBytes bounds a post-stat grower mid-stream and reads an empty file through the SDK quirk', async () => {
+    const remote = new FakeRemote()
+    remote.file('/workspace/grow.bin', [1, 1, 1, 1])
+    remote.file('/workspace/empty.bin', '')
+    const { fs } = await setup(remote)
+
+    remote.streamChunks = [bytes([1, 1, 1]), bytes([1, 2, 2])]
+    remote.streamKeepOpen = true
+    await expectCode(fs.readBytes(await fs.resolve('grow.bin'), undefined, 4), 'FS_TOO_LARGE')
+    expect(remote.streamCancel).toHaveBeenCalledOnce()
+
+    remote.streamChunks = undefined
+    remote.streamKeepOpen = false
+    expect((await fs.readBytes(await fs.resolve('empty.bin'), undefined, 4)).byteLength).toBe(0)
+  })
+
   it('honors aborts before and during remote reads', async () => {
     const remote = new FakeRemote()
     remote.file('/workspace/a', 'a')