**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.

rollup.unified.js

@@ -0,0 +1,154 @@
+import typescript from '@rollup/plugin-typescript';
+import resolve from '@rollup/plugin-node-resolve';
+import commonjs from '@rollup/plugin-commonjs';
+import json from '@rollup/plugin-json';
+import { terser } from 'rollup-plugin-terser';
+import replace from '@rollup/plugin-replace';
+
+// Custom plugin to provide empty shims for Node.js built-in modules in browser environments
+const nodeModuleShims = () => {
+  return {
+    name: 'node-module-shims',
+    resolveId(source) {
+      // List of Node.js built-in modules to shim
+      const nodeBuiltins = [
+        'fs', 'path', 'util', 'crypto', 'os', 'stream', 
+        'http', 'http2', 'https', 'zlib', 'child_process'
+      ];
+
+      if (nodeBuiltins.includes(source)) {
+        // Return a virtual module ID for the shim
+        return `\0${source}-shim`;
+      }
+      return null;
+    },
+    load(id) {
+      // If this is one of our shims, return an empty module
+      if (id.startsWith('\0') && id.endsWith('-shim')) {
+        console.log(`Providing empty shim for Node.js module: ${id.slice(1, -5)}`);
+        return 'export default {}; export const promises = {};';
+      }
+      return null;
+    }
+  };
+};
+
+// Custom plugin to fix 'this' references in specific files
+const fixThisReferences = () => {
+  return {
+    name: 'fix-this-references',
+    transform(code, id) {
+      // Only transform the specific files that have issues with 'this'
+      if (id.includes('@tensorflow/tfjs-layers/dist/layers/convolutional_recurrent.js')) {
+        // Replace 'this' with 'globalThis' in the problematic code
+        return {
+          code: code.replace(/\bthis\b/g, 'globalThis'),
+          map: { mappings: '' } // Provide an empty sourcemap to avoid warnings
+        };
+      }
+      return null; // Return null to let Rollup handle other files normally
+    }
+  };
+};
+
+export default {
+  input: 'src/unified.ts', // Use the unified entry point
+  inlineDynamicImports: true,
+  output: [
+    {
+      file: 'dist/unified.js',
+      format: 'es',
+      sourcemap: true,
+      intro: `
+// Environment detection
+const isBrowser = typeof window !== 'undefined';
+const isNode = typeof process !== 'undefined' && process.versions && process.versions.node;
+const isServerless = !isBrowser && !isNode;
+
+// Global Buffer polyfill for browser environments
+if (isBrowser) {
+  try {
+    // Import Buffer from the buffer package
+    import('buffer').then(({ Buffer }) => {
+      globalThis.Buffer = Buffer;
+    }).catch(err => {
+      console.warn('Failed to load Buffer polyfill:', err);
+    });
+  } catch (e) {
+    console.warn('Failed to import buffer package:', e);
+  }
+}
+
+// Global variable to store environment
+globalThis.__ENV__ = {
+  isBrowser,
+  isNode,
+  isServerless
+};
+      `
+    },
+    {
+      file: 'dist/unified.min.js',
+      format: 'es',
+      sourcemap: true,
+      plugins: [terser()],
+      intro: `
+// Environment detection
+const isBrowser = typeof window !== 'undefined';
+const isNode = typeof process !== 'undefined' && process.versions && process.versions.node;
+const isServerless = !isBrowser && !isNode;
+
+// Global Buffer polyfill for browser environments
+if (isBrowser) {
+  try {
+    // Import Buffer from the buffer package
+    import('buffer').then(({ Buffer }) => {
+      globalThis.Buffer = Buffer;
+    }).catch(err => {
+      console.warn('Failed to load Buffer polyfill:', err);
+    });
+  } catch (e) {
+    console.warn('Failed to import buffer package:', e);
+  }
+}
+
+// Global variable to store environment
+globalThis.__ENV__ = {
+  isBrowser,
+  isNode,
+  isServerless
+};
+      `
+    }
+  ],
+  plugins: [
+    // Add environment replacement
+    replace({
+      preventAssignment: true,
+      'process.env.NODE_ENV': JSON.stringify('production')
+    }),
+    // Add our custom plugins
+    fixThisReferences(),
+    nodeModuleShims(),
+    resolve({
+      browser: true,
+      preferBuiltins: false
+    }),
+    commonjs({
+      transformMixedEsModules: true
+    }),
+    json(),
+    typescript({
+      tsconfig: './tsconfig.unified.json',
+      declaration: true,
+      declarationMap: true
+    })
+  ],
+  external: [
+    // Add any dependencies you want to exclude from the bundle
+    '@aws-sdk/client-s3',
+    '@smithy/util-stream',
+    '@smithy/node-http-handler',
+    '@aws-crypto/crc32c'
+  ]
+};