* fix: use effective_model_for_budget instead of raw model in compaction_config
When model is set to 'auto', self.model holds the literal string 'auto',
which gets passed to the API as the model name in compaction requests.
DeepSeek's API rejects 'auto' with HTTP 400 since it's not a recognized
model ID.
effective_model_for_budget() resolves 'auto' to the last effective model
or falls back to DEFAULT_TEXT_MODEL, ensuring compaction always sends a
concrete model name.
* test(tui): cover auto model compaction config
---------
Co-authored-by: codgo <anbiaoren@gie777.com>
Co-authored-by: Hunter B <hmbown@gmail.com>
BryonGo
f7fbc35165