chore: update URLs and remove deprecated tools

Updated several URLs across multiple files for improved accuracy and accessibility. Removed deprecated tools and non-functional links to maintain relevance and efficiency in the documentation.

(This commit message was AI-generated.)

Signed-off-by: Jens Oliver Meiert <[email protected]>

Author: j9t

manuscript/book.md

@@ -14,4 +14,4 @@ Contact +34-610859489 or [email protected] for questions and more informati
 
 Follow [Frontend Dogma on Mastodon](https://mas.to/@frontenddogma) ([and other networks](https://frontenddogma.com/posts/2024/frontend-dogma-on-the-web/)).
 
-[1.5.15]
+[1.5.16]

manuscript/production.md

@@ -159,7 +159,7 @@ Accordingly, CSS routines may look like this:
 * Automated tests: on deployment, daily
 * Manual tests: on major updates, weekly
 
-Manual checks can be swift—scan the output, perhaps re-formatted to be more readable. (If browser developer tools don’t suffice for an in-depth look, web-based services like [CSSTidy](https://www.tenman.info/csstidy/css_optimiser.php) allow us to “uncompress” a style sheet.)
+Manual checks can be swift—scan the output, perhaps re-formatted to be more readable. (If browser developer tools don’t suffice for an in-depth look, web-based services like [CSSTidy](https://www.codebeautifier.com/) allow us to “uncompress” a style sheet.)
 
 Automated checks take time to be set up properly and depend on needs and priorities. Solutions include free and paid services used in conjunction with task runners or hooked up to the respective CI pipeline. A simple setup may involve making use of [Git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks) to use a script like [pre-commit](https://github.com/WouterSioen/pre-commit) to validate and lint on commit. Nowadays there are more elegant options, notably [stylelint](https://stylelint.io/).
 

manuscript/resources.md

@@ -15,7 +15,7 @@ A few handy CSS tools, for manual and automated testing:
 * [CSSJanus Left-to-Right-to-Left-ifyer script](https://code.google.com/archive/p/cssjanus/), to convert CSS directionality (LTR/RTL)
 * [CSSLint online tool](https://web.archive.org/web/20240503225408/http://csslint.net/) and [script](https://github.com/CSSLint/csslint), to identify CSS code issues
 * [CSSO package](https://www.npmjs.com/package/csso), to optimize and minify CSS
-* [CSSTidy online tool](https://www.tenman.info/csstidy/css_optimiser.php) and [script](http://csstidy.sourceforge.net/), to reformat and optimize CSS
+* [CSSTidy online tool](https://www.codebeautifier.com/) and [script](http://csstidy.sourceforge.net/), to reformat and optimize CSS
 * [Minify online tool](https://www.minifier.org/) and [script](https://github.com/matthiasmullie/minify), to minify CSS
 * [Minify package](https://www.npmjs.com/package/minify), to minify CSS
 * [ngx-unused-css package](https://www.npmjs.com/package/ngx-unused-css), to remove unused CSS (for Angular)