feat(quickadapter): add HistGradientBoostingRegressor support (#25)

feat(quickadapter): add HistGradientBoostingRegressor support (#25)

* feat(quickadapter): add HistGradientBoostingRegressor support

Add sklearn's HistGradientBoostingRegressor as a third regressor option.

- Add 'histgradientboostingregressor' to Regressor type and REGRESSORS
- Implement fit_regressor() with X_val/y_val support and early stopping
- Add native sklearn hyperparameters to get_optuna_study_model_parameters()
- Return empty callbacks list (no Optuna pruning callback support)
- Log warning when init_model is provided (not supported)

* fix(quickadapter): address PR review comments for HistGradientBoostingRegressor

* refactor(quickadapter): cleanup HistGradientBoostingRegressor integration

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
* perf(quickadapter): fine tune optuna search space for HistGradientBoostingRegressor

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
* perf(quickadapter): fine tune model hyperparameters search space by model

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
* chore(quickadapter): bump versions

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
* docs(README.md): add histgradientboostingregressor to supported regressors list

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
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Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>