Refinement cut by the run's cancel; the hero shows the refined R-work / R-free

The refinement of a placed model gets the run's cancel flag (RefinementSettings::cancel, through
CancelFlag::RunFlag), so the broker's deadline or a cancel - and Ctrl+C in rugnux - cuts a running
refinement short with what its finished trials found. RefinementResult::cancelled goes to the live
status as rugnux_live_refinement.cancelled (API, regenerated clients) and to the step's note.

Hero: once refined, the model card's headline is "R-work / R-free, refined" (e.g. 0.32 / 0.35), its
green/red still the placement verdict, the placement and fit in the context line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015CeEGgpKdfkCTJb3YNMJcu
(cherry picked from commit 395016a30c2bc2aa26fdf2cec2ced9cebe6fad80)

docs/python_client/docs/RugnuxLiveRefinement.md

@@ -6,7 +6,8 @@ The placed model refined against the merge it was placed on, as the report's REF
 
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
-**performed** | **bool** | Refinement ran to the end; false with `reason` where it failed | 
+**performed** | **bool** | Refinement ran; false with `reason` where it failed | 
+**cancelled** | **bool** | The deadline or a cancel cut the refinement short: the weight trials that ran were chosen among, the rest left out (cut before the first, the model is the placement's)  | 
 **reason** | **str** | Why refinement did not run to the end; empty otherwise | 
 **on_gpu** | **bool** |  | 
 **seconds** | **float** | Wall time of the refinement |