README: add live-demo pointer and sponsor section

Point to The Counter Earth (thecounterearth.com) as the engine's live showcase
(closed Alpha; contributors may get early access) and add a GitHub Sponsors
section at the bottom.

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

CHANGELOG.md

@@ -25,6 +25,8 @@ is promoted to the new version and `main` is tagged `vX.Y.Z`.
   identically.
 - **Docs** — a getting-started/install guide (Rojo + Wally and the drop-in `.rbxm`) and an
   "Extending SurvivorCore" guide (the `register()` API, the component/attribute model, Hooks).
+- **README** — a "See it live" pointer to [The Counter Earth](https://thecounterearth.com)
+  (the engine's closed-Alpha showcase) and a GitHub Sponsors section.
 
 ### Changed
 - The release workflow now cross-posts each tagged release to Discussions → **Announcements**

README.md

@@ -18,6 +18,13 @@ inventory, crafting, cooking, harvesting, hostile mobs & combat, achievements, a
 player persistence — without dictating your *content*. You bring your own items, world, and
 art; the engine wires up the behavior.
 
+## See it live
+
+SurvivorCore powers **[The Counter Earth](https://thecounterearth.com)** — a full survival
+game built on this engine, and its live showcase. The Counter Earth is in **closed Alpha**
+(not yet open to beta testers), but SurvivorCore contributors and engine devs may get early
+access — a good reason to [get involved](CONTRIBUTING.md). 👀
+
 ## Two ways to extend it
 
 **1. Programmatic — register content from code:**
@@ -75,6 +82,12 @@ demo/                  -- a runnable demo place that consumes the engine
 docs/architecture.md   -- how the layers fit together
 ```
 
+## Sponsor
+
+SurvivorCore is free and open source. If it's useful to you — or you just want to help the
+engine grow — you can support development via
+[GitHub Sponsors](https://github.com/sponsors/TemujinCalidius). 💛
+
 ## License
 
 [MIT](LICENSE) © 2026 Samuel Lison