mem0ai declared pg as a required peer pinned to exactly 8.11.3, so npm
auto-installed it for every user (including hosted MemoryClient users)
and failed with ERESOLVE in any project already on a newer pg.
The pin existed because pgvector.ts imported pg at module load, so
mem0ai/oss crashed without it. PGVector now loads pg through loadPeer on
initialize(), like the other optional vector stores, which lets pg and
@types/pg become optional ^8.11.x peers. @types/jest moves from peer to
dev dependencies.
Closes#3307
kartik-mem0