Per-blocking-method specialized classifiers (4 methods, 2 promoted)

v3.3 is a single classifier for "is this country-day censored?" But censorship has different mechanisms. We trained 4 specialized XGBoost classifiers (DNS / TCP / HTTP / TLS), each with the same 16-feature v3.3 input. Per-method positive rates are 2-12%, so F1 at threshold 0.5 is unfair — we added an alt-AUC promote path (strat AUC >= 0.80 AND LOCO median AUC >= 0.75 AND optimal F1 >= 0.50). HTTP-blocking (515 pos, strat AUC 0.901) and TLS-blocking (313 pos, strat AUC 0.918) clear the alt path. DNS (194 pos, AUC 0.952 but opt F1 0.484) and TCP (163 pos, AUC 0.903 but opt F1 0.389) skipped. Endpoints return available=false with honest reason for skipped methods. v3.3 stays as the default classifier — this is additive transparency for journalists asking HOW a country is blocking.