Scale + hardening release (re-cut from the mis-numbered v0.4.0 — same content, corrected version per the project's patch cadence).

Features: DbConnectionPool (PDO + mysqli) · Store::eval() + per-room server-set (cross-node fan-out B1) · Stage 8 App::globalScopeInclude() (experimental).
Scale fix: sharded TableSessionHandler write lock.
Hardening: session / cache / store-counter / WebSocket / pub-sub-middleware / RedisStreams / in-memory-session audit batches.
BC: HaltException extends \Error (#194); Counter::raw() returns Atomic\Long (64-bit).