chore(stylelint-config): add package metadata

[YfengJ]

Summary

• add npm repository metadata with the package directory for the stylelint config package
• add npm bugs.url metadata pointing to the repository issue tracker
• leave runtime code, dependencies, generated files, package exports, and version fields unchanged

Validation

• node package manifest assertion for repository and bugs.url
• npm pack --dry-run --ignore-scripts --json from packages/stylelint-config
• git diff --check