**feat: add browser-compatible build configuration and environment detection**

### Changes:
- Added `rollup.unified.js` for building a unified bundle with environment detection (Node.js, Browser, Serverless).
- Added `rollup_config.js` for browser-specific bundle configurations.
- Created `tsconfig.browser.json` for browser builds and `tsconfig.unified.json` for unified builds.
- Implemented custom Rollup plugins:
  - **`fixThisReferences`**: Resolves `this` reference issues in TensorFlow files.
  - **`nodeModuleShims`**: Provides empty shims for Node.js built-in modules in browser environments.
- Updated dependencies in `package-lock.json` to include Rollup plugins and updated `buffer` dependency for polyfills.
- Created `src/unified.ts` as the unified library entry point with dynamic environment detection.

### Purpose:
- Introduced a unified and browser-compatible build pipeline to ensure `Brainy` can seamlessly operate across multiple environments (Node.js, Browser, Serverless).
- Resolved compatibility issues with Node.js modules and specific library builds.
- Enhanced flexibility and usability for developers working in diverse runtime environments.

tsconfig.browser.json

@@ -0,0 +1,30 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "esModuleInterop": true,
+    "strict": true,
+    "declaration": false,
+    "outDir": "./dist",
+    "rootDir": ".",
+    "lib": [
+      "DOM",
+      "ESNext"
+    ],
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "noEmit": false,
+    "preserveConstEnums": true,
+    "sourceMap": true
+  },
+  "include": [
+    "src/**/*",
+    "examples/**/*"
+  ],
+  "exclude": [
+    "node_modules",
+    "dist",
+    "**/*.test.ts"
+  ]
+}