docs: replace nonexistent test:all script with npm test

[FirmaSpring]

Problem

The contributor checklist in docs/CONTRIBUTING.md tells contributors to run npm run test:all, but no script named test:all exists in package.json. Following the documented step fails:

$ npm run test:all
npm error Missing script: "test:all"
npm error
npm error Did you mean one of these?
npm error   npm install # Install a package
npm error   npm run test:cjs # run the "test:cjs" package script

Solution

Replace npm run test:all with npm test in the checklist. The test script in package.json runs the full suite (build:reset, build:docs, test:specs, test:unit, test:umd, test:cjs, test:types, test:lint), which is the complete check a contributor needs before submitting.

Verification

• Confirmed test:all does not exist in package.json (rg '"test' package.json lists all test scripts; none is test:all).
• Confirmed npm run test:all fails with "Missing script".
• Confirmed npm test is the full-suite script defined in package.json.

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