feat(src/brainyData, src/utils): enhance embedding efficiency with batch processing and initialize safeguards

- Added batch embedding support with `defaultBatchEmbeddingFunction`, leveraging shared model instances for optimized performance.
- Integrated `isInitializing` flag to prevent recursive initialization and ensure smooth concurrent operation handling during `BrainyData` initialization.
- Pre-loaded Universal Sentence Encoder in `BrainyData` to prevent delays during embedding.
- Introduced fallback mechanisms in embedding initialization for better error resiliency and model reusability.
- Updated `addBatch` with support for batchSize and refactored text/vector processing logic for clearer separation and memory management.
- Improved GPU and CPU backend selection in Universal Sentence Encoder for compatibility across environments.
- Enhanced memory management by cleaning tensors after embedding operations.
- Updated README with instructions for batch embedding, threading updates, and GPU/CPU optimizations.

src/utils/environment.ts

@@ -39,7 +39,7 @@ export function areWebWorkersAvailable(): boolean {
  */
 export function areWorkerThreadsAvailable(): boolean {
   if (!isNode()) return false;
-  
+
   try {
     // Dynamic import to avoid errors in browser environments
     require('worker_threads');
@@ -51,7 +51,8 @@ export function areWorkerThreadsAvailable(): boolean {
 
 /**
  * Determine if threading is available in the current environment
+ * Always returns false since multithreading has been removed
  */
 export function isThreadingAvailable(): boolean {
-  return areWebWorkersAvailable() || areWorkerThreadsAvailable();
+  return false;
 }