**feat: add global type declarations for environment detection**

### Changes:
- Introduced `global.d.ts` to define global type declarations for the `globalThis` interface.
- Added `__ENV__` object with the following properties:
  - `isBrowser: boolean`
  - `isNode: string | false`
  - `isServerless: boolean`
- Included an export statement to ensure the file is treated as a module.

### Purpose:
Defined global environment properties to standardize and enhance environment detection across browser, Node.js, and serverless environments. This improves type safety and consistency in the codebase.

src/global.d.ts

@@ -0,0 +1,15 @@
+/**
+ * Global type declarations for Brainy
+ */
+
+// Extend the globalThis interface to include the __ENV__ property
+declare global {
+  var __ENV__: {
+    isBrowser: boolean;
+    isNode: string | false;
+    isServerless: boolean;
+  };
+}
+
+// This export is needed to make this file a module
+export {};