docs: add Star History chart to end of READMEs

Appends a star-history.com chart (light/dark via <picture>) to the end of
the English, Spanish, and Korean READMEs. Heading follows each file's
convention: translated in Spanish ("Historial de estrellas"), English
elsewhere.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.es.md

@@ -255,3 +255,13 @@ Ya sabes exactamente por qué.
 ## Licencia
 
 [MIT](LICENSE). La licencia más corta que funciona.
+
+## Historial de estrellas
+
+<a href="https://www.star-history.com/dietrichgebert/ponytail#history">
+ <picture>
+   <source media="(prefers-color-scheme: dark)" srcset="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date&theme=dark" />
+   <source media="(prefers-color-scheme: light)" srcset="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date" />
+   <img alt="Star History Chart" src="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date" />
+ </picture>
+</a>

README.ko.md

@@ -275,3 +275,13 @@ OpenClaw 스킬 패키지(`.openclaw/skills/`)는 `skills/`에서 생성된다.
 ## License
 
 [MIT](LICENSE). 돌아가는 가장 짧은 라이선스.
+
+## Star History
+
+<a href="https://www.star-history.com/dietrichgebert/ponytail#history">
+ <picture>
+   <source media="(prefers-color-scheme: dark)" srcset="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date&theme=dark" />
+   <source media="(prefers-color-scheme: light)" srcset="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date" />
+   <img alt="Star History Chart" src="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date" />
+ </picture>
+</a>

README.md

@@ -286,3 +286,13 @@ You know exactly why.
 ## License
 
 [MIT](LICENSE). The shortest license that works.
+
+## Star History
+
+<a href="https://www.star-history.com/dietrichgebert/ponytail#history">
+ <picture>
+   <source media="(prefers-color-scheme: dark)" srcset="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date&theme=dark" />
+   <source media="(prefers-color-scheme: light)" srcset="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date" />
+   <img alt="Star History Chart" src="https://api.star-history.com/chart?repos=DietrichGebert/ponytail&type=Date" />
+ </picture>
+</a>