docs: rename the native provider to @soulcraft/cor across public docs and JSDoc

The 3.0 native engine ships as @soulcraft/cor (brainy 8.x <-> cor 3.x are a
version-matched pair); the old @soulcraft/cortex package stays on the 2.x/7.x
line. Public docs and .d.ts-visible comments now name the correct package.
Historical 2.x contract references (e.g. the 2.3.1 read-side fallback) keep
the old name deliberately.

src/embeddings/EmbeddingManager.ts

@@ -60,7 +60,7 @@ export class EmbeddingManager {
   private constructor() {
     this.engine = WASMEmbeddingEngine.getInstance()
     // Log deferred to init() — at construction time we don't know if a plugin
-    // (like Cortex) will replace the WASM embedder with a native one.
+    // (like Cor) will replace the WASM embedder with a native one.
   }
 
   /**