v0.150.0

release: cut v0.150.0

Stabilization cycle landing the verified-real findings from a
ship-readiness review of the C codebase. Highlights: nine more
realloc-overwrite leaks in src/prim/string.c follow the canonical
temp-pointer pattern; a checked-size helper trio (checked_add_sz /
checked_mul_sz / checked_double_sz) guards growth arithmetic across
env, state, module, eval/read, and prim/io; gc_pin asserts on
overflow in debug builds; mino_safepoint_poll becomes a static
inline; add-load-path! prefers memcpy when the length is known; the
stale dyn_snapshot TODO is replaced with a description of what the
field actually holds; embed_stm_test no longer crashes on small-
integer agent values (six sites route through mino_to_int). See
CHANGELOG.md for the full set.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>