#spec-059

Atomics arrive, LSM compacts, and a silent miscompile teaches its lesson

Twenty commits since this morning. SPEC-059 atomics landed Phases A and B. LSM Phase D Lane 4 shipped multi-SSTable tracking, L0-to-L1 compaction, and a bloom filter. STL Phase 2 brought canonical byte encoding. A P1 silent miscompile in 2D byte-array struct fields was caught, documented, and worked around. The compiler now warns on type-shaped expressions at value position. The record continues.