feat: add changeset validation and release workflow

[bjohansebas]

Summary

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[Copilot]

Pull request overview

This PR introduces a Changesets-based release process for webpack-dev-server, adds CI validation for changeset files, and wires up an automated release workflow that opens release PRs and publishes to npm from main.

Changes:

• Add Changesets tooling/config (config, changelog generator, and initial changeset) and a changeset validation script.
• Add a GitHub Actions Release workflow using changesets/action and update CI lint workflow to validate changeset format on PRs.
• Update project metadata/docs: add new npm scripts/dependencies, remove standard-version, and document changesets in CONTRIBUTING.md.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
package.json	Adds changeset tooling + validation script; removes standard-version release script/dependency.
CONTRIBUTING.md	Documents when/how to add changesets and how releases are produced.
.github/workflows/release.yml	Adds CI release workflow using changesets/action on pushes to main.
.github/workflows/nodejs.yml	Adds a PR-only step to validate changeset frontmatter format.
.github/dependabot.yml	Adds Dependabot updates for GitHub Actions.
.changeset/README.md	Adds Changesets-generated README for contributor context.
.changeset/fix-hmr-skip-user-proxy-upgrade.md	Adds a patch changeset entry for an existing behavior change.
.changeset/config.json	Adds Changesets configuration (base branch, changelog generator, etc.).
.changeset/changeset-validate.mjs	Adds a script to validate changeset frontmatter entries in PRs/local changes.
.changeset/changelog-generator.mjs	Adds a custom changelog generator integrating GitHub PR/commit/user links.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.61%. Comparing base (948d5e6) to head (697c64f).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #5680 +/- ##
=======================================
Coverage 83.61% 83.61% =======================================
Files 13 13 Lines 2087 2087 Branches 774 775 +1 =======================================
Hits 1745 1745 Misses 306 306 Partials 36 36 

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