Use npm ci instead of npm install in build.rs

[ChristianPavilonis]

Summary

• Switch build.rs from npm install to npm ci so that building on a fresh worktree does not modify package-lock.json and pollute diffs.

Changes

File	Change
crates/js/build.rs	Changed .arg("install") to .arg("ci") and updated warning message

Closes

Closes #378

Test plan

• cargo test --workspace
• cargo clippy --all-targets --all-features -- -D warnings
• cargo fmt --all -- --check
• JS tests: cd crates/js/lib && npx vitest run
• JS format: cd crates/js/lib && npm run format
• Docs format: cd docs && npm run format
• WASM build: cargo build --bin trusted-server-fastly --release --target wasm32-wasip1

Checklist

• Changes follow CLAUDE.md conventions
• No unwrap() in production code — use expect("should ...")
• Uses tracing macros (not println!)
• New code has tests
• No secrets or credentials committed

[aram356]

Thanks for finding this:

can you please update docs:

./guide/error-reference.md:npm install
./README.md:npm install

[aram356]

👍 Looks good. Please merge it.