dev env: Change app deployment script to use gh-pages

## Issue 1
**Problem:**
https://github.com/kottans/framework-2021/commit/a8e06addcc7adc7a079edf5006185e5ac7333ffa (currently on dev) brings back `push-dir` as a publishing script.
Alternative deployment package `gh-pages` is already listed among dev dependencies.

**Desired outcome:**
`gh-pages` is used as a publishing method.

**Suggested approach:**
`package.json`: change `deploy` script so that it runs `gh-pages -d dist`

## Issue 2

**Problem:**
https://github.com/kottans/framework-2021/commit/a8e06addcc7adc7a079edf5006185e5ac7333ffa (currently on dev) brings back shell interpretation of glob passed to `npx prettier`.

**Desired outcome:**
`npx prettier` glob is quoted and therefore interpreted by prettier, not shell.

**Suggested approach:**
`package.json`: change `prettify` script so that it runs `npx prettier --write \"**/*.{js,css,md,html}\"`