feat: implement clean embedding architecture with Q8/FP32 precision control

- Unified embedding system with single EmbeddingManager
- Q8 model support with 75% smaller footprint (23MB vs 90MB)
- Intelligent precision auto-selection based on environment
- Clean cached embeddings with TTL and memory management
- Zero-config setup with smart defaults
- Complete storage structure documentation
- Removed legacy worker and hybrid managers
- Streamlined model configuration and precision management

src/embeddings/index.ts

@@ -0,0 +1,28 @@
+/**
+ * Embeddings Module - Clean, Unified Architecture
+ * 
+ * This module provides all embedding functionality for Brainy.
+ * 
+ * Main Components:
+ * - EmbeddingManager: Core embedding generation with Q8/FP32 support
+ * - CachedEmbeddings: Performance optimization layer with pre-computed embeddings
+ */
+
+// Core embedding functionality
+export { 
+  EmbeddingManager, 
+  embeddingManager, 
+  embed, 
+  getEmbeddingFunction,
+  getEmbeddingStats,
+  type ModelPrecision
+} from './EmbeddingManager.js'
+
+// Cached embeddings for performance
+export { 
+  CachedEmbeddings, 
+  cachedEmbeddings 
+} from './CachedEmbeddings.js'
+
+// Default export is the singleton manager
+export { embeddingManager as default } from './EmbeddingManager.js'