Rebase Vite/Vitest tooling onto prover stack (self-contained IIFE, external bfj)

[OBrezhniev]

Rebase tooling migration onto our prover stack (Vite + Vitest)

Applies the feat/esm-migration build/test tooling on top of our
feature/memory-scoping prover-optimization work. Target: feat/esm-migration.

Keeps all of our work and behaviour:

• src unchanged: groth16_prove.js (buildABCStream witness gather,
  msmBatching/msmGlv/msmGls options, --memlog/memoryLogging),
  cli.js (--memlog, msm options), noble-hashes v2 import paths. Only removed
  a redundant /* global window */.
• Self-contained IIFE preserved. The Vite iife build bundles
  ffjavascript/binfileutils/r1csfile so a bare <script src="snarkjs.min.js">
  still exposes a working window.snarkjs — this branch's iife externalises
  them as globals, which breaks that usage. Node built-ins and the wasm codegen
  toolchain are stubbed via resolve.alias (build-config/), reproducing the
  old rollup virtual stubs; snarkjs.min.js 763 → 569 KB.
• bfj/ejs kept in dependencies (external + lazily required in the CLI)
  so startup stays fast and JSON/Solidity exports still work. (This branch moved
  bfj to devDeps + bundled it.)
• exports keeps node import/require + browser + umd (snarkjs.min.js).

Validation: lint clean; 59 node tests (fullprocess/fflonk/keypar/polynomial)

• 10 browser tests (Playwright/chromium) pass; built CLI prove+verify (OK!)
  with --memlog, and bfj r1cs-json export verified.

Not included: the test/smart_contracts.test.js Hardhat/ethers Solidity-verifier
test — it needs a Solidity build toolchain and is a net-new capability, better
ported on its own. The unminified build/snarkjs.js is dropped (only the
umd-referenced snarkjs.min.js is built).

[OBrezhniev]

ESM-rebase set — the tooling migration re-applied on top of our optimization stack (rather than replaying the branches), so the MSM/CIOS/memory work is preserved. Review together:

• Rebase ESM + Vite/Vitest onto CIOS/MSM stack wasmcurves#76 (full CJS→ESM; keeps our CIOS/GLV hot files)
• Rebase Vite/Vitest tooling onto MSM stack (build/test only, no threadman rewrite) ffjavascript#186 (Vite/Vitest only — WorkerSlot/batch-MSM threadman kept, no workerpool)
• Rebase Vite/Vitest tooling onto direct-io stack fastfile#137 · Rebase Vite/Vitest tooling onto our stack (keep MAX_BUFFER_SIZE fix) binfileutils#89 · Rebase Vite/Vitest tooling onto deps-update stack r1csfile#106
• Rebase Vite/Vitest tooling onto prover stack (self-contained IIFE, external bfj) #629 (self-contained IIFE + external-lazy bfj kept)

Deviations from feat/esm-migration are called out in each PR body (e.g. binfileutils MAX_BUFFER_SIZE, snarkjs IIFE/bfj, mnt6753 excluded, smart_contracts test deferred). All branches keep git+https commit-ref pins; re-pin if a branch moves.