feat: Add GitHub Actions CI (lint + tests)

[srijnabhargav]

PR description

This PR adds a GitHub Actions workflow so every pull request and push to main runs the same checks developers use locally: install dependencies, ESLint, and Node regression tests (node --test).

Changes

• Add .github/workflows/ci.yml: checkout, Node 20, cache npm, install root + src/server deps, npm run lint, npm test.
• Use npm ci --legacy-peer-deps for the root install so CI matches the repo’s peer-dependency resolution (plain npm ci fails on the current webpack / uglifyjs-webpack-plugin peer range).
• Add .github/README.md with instructions to enable branch protection and require the CI status check before merging (manual step in repo Settings → Branches).
• Apply ESLint --fix on src/server/app.js so lint passes under the existing .eslintrc rules.

AI-assisted contribution disclosure - Mostly AI-generate

[srijnabhargav]

Please check: #128 (comment)

[Sing-Li]

@srijnabhargav I cannot get the action to successfully complete.

seems to be complaining that dotenv version missing in the package.lock

[srijnabhargav]

Hello sir, master branch changed again 😅 and the synced lockfiles were added back upstream, so I realigned this branch with that.

I merged latest master and switched the workflow back to the lockfile-based setup: npm ci --legacy-peer-deps at the root, npm --prefix src/server ci, and restored npm caching.

[Sing-Li]

Double path problem.

[srijnabhargav]

ci is green now 🥳🥳

[Sing-Li]

Awesome. LGTM