feat: replace transformers.js with direct ONNX WASM for Bun compatibility

- Remove @huggingface/transformers dependency (539MB native binaries)
- Add direct ONNX Runtime Web embedding engine
- Bundle all-MiniLM-L6-v2-q8 model (24MB, no runtime downloads)
- Works with Node.js, Bun, and bun build --compile
- Air-gap compatible: fully self-contained, no internet required

New WASM embedding components:
- WASMEmbeddingEngine: Main integration class
- WordPieceTokenizer: Pure TypeScript tokenizer
- EmbeddingPostProcessor: Mean pooling + L2 normalization
- ONNXInferenceEngine: Direct ONNX Runtime Web wrapper
- AssetLoader: Model file loading

Tests added:
- 11 WASM embedding integration tests
- 8 Bun compatibility tests

New npm scripts:
- test:wasm - Run WASM embedding tests
- test:bun - Run tests with Bun
- test:bun:compile - Build and run compiled binary

src/setup.ts

@@ -1,46 +1,31 @@
 /**
- * CRITICAL: This file is imported for its side effects to patch the environment
- * for Node.js compatibility before any other library code runs.
+ * Brainy Setup - Minimal Polyfills
  *
- * It ensures that by the time Transformers.js/ONNX Runtime is imported by any other
- * module, the necessary compatibility fixes for the current Node.js
- * environment are already in place.
+ * ARCHITECTURE (v7.0.0):
+ * Brainy uses direct ONNX WASM for embeddings.
+ * No transformers.js dependency, no hacks required.
  *
- * This file MUST be imported as the first import in unified.ts to prevent
- * race conditions with library initialization. Failure to do so may
- * result in errors like "TextEncoder is not a constructor" when the package
- * is used in Node.js environments.
+ * This file provides minimal polyfills for cross-environment compatibility:
+ * - TextEncoder/TextDecoder for older environments
  *
- * The package.json file marks this file as having side effects to prevent
- * tree-shaking by bundlers, ensuring the patch is always applied.
+ * BENEFITS:
+ * - Clean codebase with no workarounds
+ * - Works everywhere: Node.js, Bun, Bun --compile, browsers, Deno
+ * - No platform-specific binaries
+ * - Model bundled in package (no runtime downloads)
  */
 
-// Get the appropriate global object for the current environment
-const globalObj = (() => {
-  if (typeof globalThis !== 'undefined') return globalThis
-  if (typeof global !== 'undefined') return global
-  if (typeof self !== 'undefined') return self
-  return null // No global object available
-})()
+// ============================================================================
+// TextEncoder/TextDecoder Polyfills
+// ============================================================================
+const globalObj = globalThis ?? global ?? self
 
-// Define TextEncoder and TextDecoder globally to make sure they're available
-// Now works across all environments: Node.js, serverless, and other server environments
 if (globalObj) {
-  if (!globalObj.TextEncoder) {
-    globalObj.TextEncoder = TextEncoder
-  }
-  if (!globalObj.TextDecoder) {
-    globalObj.TextDecoder = TextDecoder
-  }
-  
-  // Create special global constructors for library compatibility
-  (globalObj as any).__TextEncoder__ = TextEncoder
+  if (!globalObj.TextEncoder) globalObj.TextEncoder = TextEncoder
+  if (!globalObj.TextDecoder) globalObj.TextDecoder = TextDecoder
+  ;(globalObj as any).__TextEncoder__ = TextEncoder
   ;(globalObj as any).__TextDecoder__ = TextDecoder
 }
 
-// Also import normally for ES modules environments
 import { applyTensorFlowPatch } from './utils/textEncoding.js'
-
-// Apply the TextEncoder/TextDecoder compatibility patch
 applyTensorFlowPatch()
-console.log('Applied TextEncoder/TextDecoder patch via ES modules in setup.ts')