docs(readme): add Star History chart section

Renders the star-history.com chart (light/dark) at the end of the README.

Author: DemchaAV

README.md

@@ -243,3 +243,13 @@ Full detail: [architecture overview](./docs/architecture/overview.md) · [
 ## License
 
 MIT — see [`LICENSE`](./LICENSE).
+
+## Star History
+
+<a href="https://www.star-history.com/?repos=DemchaAV%2FGraphCompose&type=date&legend=top-left">
+ <picture>
+   <source media="(prefers-color-scheme: dark)" srcset="https://api.star-history.com/chart?repos=DemchaAV/GraphCompose&type=date&theme=dark&legend=top-left" />
+   <source media="(prefers-color-scheme: light)" srcset="https://api.star-history.com/chart?repos=DemchaAV/GraphCompose&type=date&legend=top-left" />
+   <img alt="Star History Chart" src="https://api.star-history.com/chart?repos=DemchaAV/GraphCompose&type=date&legend=top-left" />
+ </picture>
+</a>