Is your feature request related to a problem? Please describe.

Title

Feature: Add Node test coverage report for CI

Summary

Add a Node.js test coverage report (c8 + mocha) for easy local view of line/branch/statement coverage and potentially add to CI in the future

Motivation

• Provide coverage metrics for mocha tests.
• Help track coverage regressions and ensure Node-specific adapter behavior is exercised.
• Useful for code review and future refactors or adding test coverage.

Describe the solution you'd like

Proposed change

• Add scripts/test:node:coverage script that runs c8 with the Node test suite.
• Add minimal c8 config if required.
• Add CI job that runs Node tests and uploads coverage artifact (or posts to coverage service).
• Keep browser tests and existing CI unaffected.

Implementation details

• Add dependency: c8 (devDependency).
• Scripts example:
  • test:node-coverage
  • "c8": { "all": true, "include": [ "lib/**/*.js", "lib/**/*.ts" ], "exclude": [ "test", "sandbox" ], "reporter": [ "text", "lcov", "html" ], "report-dir": "./coverage" },

Describe alternatives you've considered

No response

Additional context/Screenshots