Add four Pantechnicon browser tools

[csharpsensei]

Four tools from pantechnicon.dev, one per relevant section, inserted in alphabetical order.

Against CONTRIBUTING.md:

• Browser-based — all four run entirely client-side. The site loads no third-party scripts at all, so there is nothing to install and nothing phoning home. Verifiable in the Network tab.
• Direct link — each entry points at a single tool page, not the homepage.
• 100% free — no signup, no account, no cap, no paid tier on any of these pages.

Happy to trim to fewer entries or move any of them to a different section if you'd prefer.

[github-actions]

Hey csharpsensei! Thanks for your submission! 🚀

To keep awesome-devtools instantly accessible for everyone, all tools must be:

• Browser-based — no downloads or native app installs
• Direct link — goes straight to the tool (not a multi-tool landing page)
• 100% free — no signups, trials, paywalls, or usage limits

Please make sure your PR meets these criteria. It may take some time for your submission to be reviewed — you can occasionally comment with a "bump" to bring more attention to it.

Thanks for contributing! 🙌