[codex] harden wasm bindings

[rosssaunders]

Summary

• Add shared WASM boundary validation helpers that convert invalid inputs into JS errors.
• Harden pricing, Heston, payoff, risk, and credit WASM exports against invalid scalar inputs and mismatched typed-array lengths.
• Add Node-based wasm-bindgen-test contract tests and CI coverage for the generated WASM package.
• Add a WASM binary size budget check and update repo docs with the new test command.
• Fix a clippy warning in a correlation test loop that blocked the repository pre-commit hook.

Validation

• cargo test -p openferric-wasm
• wasm-pack test --node wasm
• wasm-pack build wasm --target web --out-dir ../www/pkg
• cargo fmt --all --check
• cargo clippy -p openferric-wasm --all-targets
• pre-commit hook: fmt, clippy, eslint, tsc, ruff check, ruff format

Notes

Unrelated local dirty files were left out of this PR: vendor/QuantLib, vscode-ext/dist/extension.js, and vscode-ext/server/openferric-lsp.