* fix(client): stabilize reasoning_content replay for prompt cache
- stop gating assistant reasoning_content on whether a later user turn
exists; the field now depends only on the stored message itself
- preserve historical message bytes across turns so DeepSeek's prefix
cache stays warm on every text-reply follow-up
- add a byte-stability regression test and update the prior-non-tool
reasoning test to assert the new contract
* style(client): rustfmt single-line let binding
- collapse a two-line `let mut has_reasoning = ...` into a single line
so `cargo fmt --all -- --check` passes
Duducoco
e10e53d396