Funding: enable Ko-fi link, mention it in README support section

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Shadetail

.github/FUNDING.yml

@@ -1,2 +1,2 @@
 github: Shadetail
-# ko_fi: <name>        # uncomment when a Ko-fi account is set up
+ko_fi: shadetaileagleshadow

README.md

@@ -135,5 +135,6 @@ GPLv3 — see [LICENSE](LICENSE). Third-party components are MIT-licensed; see
 Bug reports and feature requests are welcome in
 [Issues](https://github.com/Shadetail/HDRScopes/issues) — this is a hobby
 project, so support is best-effort. If HDRScopes is useful to you, a star
-helps others find it, and sponsorship (button up top) is appreciated but
-never expected.
+helps others find it, and a donation via
+[Ko-fi](https://ko-fi.com/shadetaileagleshadow) or the Sponsor button up top
+is appreciated but never expected.