sketch_bloom.nx

sketch_bloom.nx -- Bloom filter v2 (sovereign-tier with typed envelope). Burton Howard Bloom 1970. Tracks n_inserted so the FPR envelope reflects ACTUAL load, not just design-time spec. Companion to the older runtime/bloom.nx (which lacks the envelope + counted state + proper FPR-by-load reporting). FPR FORMULA (Bloom 1970): FPR = (1 - e^(-kn/m))^k For k = (m/n) ln(2) optimal: FPR = 0.6185^(m/n) We can't compute exp / pow in i64-only. Conservative approach: tabulate FPR-by-(m/n) at integer ratios assuming OPTIMAL k. If the caller chose non-optimal k, real FPR is worse than reported -- we document this. v2 will swap in a tighter integer approximation. LOSSLESS-LANGUAGE DISCIPLINE (doc 20): contains -> 1 means "probably present" with envelope FPR; 0 means "definitely absent" with envelope FPR = 0. Both cases ship the ApproxI64 with NX_ENV_ABS / conf_ppb = 1e9 - fpr_ppb. Complements sketch_cuckoo.nx (which supports delete). Bloom is more space-efficient at high FPR; Cuckoo wins below ~3% FPR with delete.