[CI] Add Testing Workflow

[rasulkireev]

Summary

• Add a pull request CI workflow that installs dependencies with npm ci, typechecks, runs tests, and builds the plugin on Node.js 20.
• Add local typecheck, test, and ci npm scripts so contributors can run the same checks before pushing.
• Add a first Node.js built-in test suite for the status bar queue behavior.
• Update the release workflow to use the same clean install and validation path before publishing.
• Pin obsidian to the npm 1.12.3 package so clean installs are reproducible instead of depending on the moving GitHub master tarball.

Why

This gives open source contributors a simple, reliable validation path and makes future plugin changes safer. During setup, the existing Obsidian GitHub tarball dependency failed clean install integrity checks because the branch tarball moved after the lockfile was generated, so the dependency is now pinned to a published package version.

Validation

• npm ci
• npm run ci