Post-A.5 polish Priority 3. EntityClassificationCache keyed by
(entityId, landblockHint) tuple. Entity dispatcher cpu_us median ~1.2 ms,
p95 ~1.5 ms — ~66% reduction vs pre-Tier-1 baseline. Closes the
post-A.5 polish phase entirely (#52, #54, #53 all closed).
See docs/ISSUES.md #53 closure + memory/project_tier1_cache.md for the
24-commit chain, 4 bug-fix iterations, and the per-tuple-vs-per-entity
recurring trap pattern documented for future cache work.
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