MPSBoost 0.2.0a0 Release Audit

0.2.0a0 was the first functional MPS regressor alpha. It replaced pure planning APIs with a compiled native extension and the first real regression training path.

Included:

• compiled native package foundation;
• device diagnostics and MPS availability checks;
• deterministic dense-data validation and quantization groundwork;
• first functional regression estimator path.

Not included:

• optimized GPU hot path;
• cache stability guarantees;
• formal 0.2.0 release verification;
• tree-family breadth beyond the early regressor.