chore(prim/vendor): refresh wasm with -Oz size optimization

Updated vendor/acorn-wasm/acorn_wasm.wasm to ultrathink commit
b2e92f848 (wasm-opt -Oz instead of -O4). Modest 12KB shrink because
cargo's -Os profile + thin-LTO had already done most of the work,
but trims real fat. prim audit on socket-lib src/ holds at 202 sites
across 71 distinct primordials — no behavior change.

The remaining 3.90MB has structural reasons (rust-std + wasm-bindgen
glue + serde-wasm-bindgen + bumpalo). Getting to the README's 220KB
target requires replacing those dependencies, not optimizer tuning;
multi-day work, separate effort.

Author: jdalton