Fix Docker build and improve checks #220

This commit improves multiple aspects of Docker builds:

- Enable artifact output validation for Dockerfile.
- Correct the path references in Dockerfile for the distribution
  directory.
- Add Dockerfile specific indentation rules to `.editorconfig`.
- Use `npm run install-deps` for dependency installation, enhancing
  build reliability.
- Add automation script `verify-web-server-status.js` to verify running
  web server on given URL.
- Introduce automated build verification for Dockerfile:
  - On macOS, install Docker with colima as the container runtime
    because default agents do not include Docker and Docker runtime is
    not installed due to licensing issues (see actions/runner-images#17).
  - On Windows, there's no Linux container support (actions/runner#904,
    actions/runner-images#1143), so keep the checks for macOS and Ubuntu
    only.

README.md

@@ -66,8 +66,8 @@
   </a>
   <a href="https://github.com/undergroundwires/privacy.sexy/actions/workflows/checks.build.yaml" target="_blank" rel="noopener noreferrer">
     <img
-      alt="Build checks status"
-      src="https://github.com/undergroundwires/privacy.sexy/workflows/build-checks/badge.svg"
+      alt="Status of build checks"
+      src="https://github.com/undergroundwires/privacy.sexy/workflows/checks.build/badge.svg"
     />
   </a>
   <a href="https://github.com/undergroundwires/privacy.sexy/actions/workflows/checks.desktop-runtime-errors.yaml" target="_blank" rel="noopener noreferrer">