fix: hardcode version in src (#116)

[AquaticAzelf]

Fixes #116

• Hardcode version in src/index.js to "4.0.0" (synced with package.json)
• Removes import { version } from '../package.json' to avoid bundler / JSON import issues

Verification (Node 24):

• package.json version is 4.0.0
• grep -r "package.json" src/ is empty
• npm install --ignore-engines succeeds; gulp travis fails on Node 24 due to primordials is not defined (gulp 3.9.1 requires Node 14) – build verification skipped per instructions, change is conceptual/lib build would pick up hardcoded version