#677 SB anchor matched 0 comps on real prod addresses (live golden KPI 67% vs 95% sim).
Rewrites _normalize_building_key to be format-invariant: strips city/r-n/mkr/dot-tail,
drops street-type words from either side (Олимпийская наб. <-> набережная), tolerant
house parse (',', 'д.', '/N', 'кN', glued corpus letter), ё->е + street alias on full
multi-word core. Validated on live DB: Ткачёва 13->27, Б.Ельцина 6->44, Олимп 13->5,
Сакко 99->4, Февральской 21->3 (all were 0); 13!=130/131, 99!=100 over-match guarded.
ruff clean; 30 anchor tests (12 new); no #677 weighting/guardrail change; behind flag.
Refs #651#652#677
