chore: add Sponsor button and FUNDING.yml

Adds GitHub Sponsors funding metadata (.github/FUNDING.yml) so the
'Sponsor' button appears on the repo header, and a matching shield
in the README badge row.

Defaults to GitHub Sponsors with handle 'TMHSDigital'. To add other
platforms (Buy Me a Coffee, Ko-fi, Open Collective, custom URL),
extend .github/FUNDING.yml per:
https://docs.github.com/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/displaying-a-sponsor-button-in-your-repository

Signed-off-by: 154358121+TMHSDigital@users.noreply.github.com
Made-with: Cursor

Author: TMHSDigital

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: [TMHSDigital]

README.md

@@ -17,6 +17,7 @@
  <a href="https://github.com/TMHSDigital/Developer-Tools-Directory/actions/workflows/codeql.yml"><img src="https://github.com/TMHSDigital/Developer-Tools-Directory/actions/workflows/codeql.yml/badge.svg" alt="CodeQL" /></a>
  <a href="https://www.python.org/"><img src="https://img.shields.io/badge/python-3.12+-3776ab?logo=python&logoColor=white" alt="Python 3.12+" /></a>
  <a href="CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen" alt="PRs Welcome" /></a>
+ <a href="https://github.com/sponsors/TMHSDigital"><img src="https://img.shields.io/badge/sponsor-%E2%9D%A4-EA4AAA?logo=githubsponsors&logoColor=white" alt="Sponsor" /></a>
 </p>
 
 <p align="center">