fix: restore h3_repr_steering's clone -- out can alias the block loop's own tensor

Adversarial review round 1 caught this: out is not provably this hook's own
private tensor. A chained h3_block_repeat span_loop passthrough returns
args["img"] verbatim with no copy for non-head blocks in its span, and
h3_repr_steering installs as the OUTER wrapper around it (_install_block_
influence then _install_h3_repr_steering in _sample_chunk) -- so `out` here
can be the H3 model loop's own live `h`. Removing the clone entirely (as the
previous commit did) reintroduced exactly the aliasing hazard block_repeat's
own _repeat() explicitly guards against one function away. Restored the
clone, kept unconditional (not gated behind the safe/unsafe branch) so it
still doesn't need the host sync this fix exists to remove.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

samplers.py

@@ -6943,6 +6943,14 @@ class FunPackLTXAVSceneChainSampler:
                             bump = (direction.to(out.dtype).to(out.device)
                                     * _strength * row_norm.to(out.dtype))
                             safe = torch.isfinite(row_norm) & (row_norm > 0)
+                            # Clone unconditionally (not gated behind the safe/unsafe check --
+                            # that would need the exact host sync this rewrite exists to avoid).
+                            # `out` is NOT provably this hook's own private tensor: a chained
+                            # span_loop passthrough (samplers.py's block-repeat span mode)
+                            # returns args["img"] verbatim with no copy, which can be the H3
+                            # model loop's own live `h` -- mutating it in place would corrupt
+                            # that loop's state for any block this hook shares with span_loop.
+                            out = out.clone()
                             out[mask] = torch.where(safe, rows + bump.to(rows.dtype), rows)
                     return {"img": out}
                 return _tag_dit_hook(_hook, inner)