feat\!: migrate from TensorFlow.js to Transformers.js with ONNX Runtime

BREAKING CHANGE: Complete migration from TensorFlow.js to Transformers.js for embedding generation

This is a major architectural change that replaces TensorFlow.js (USE model) with Transformers.js (all-MiniLM-L6-v2) for significantly improved performance and reduced complexity.

Key Changes:
- Replace TensorFlow.js Universal Sentence Encoder with Transformers.js all-MiniLM-L6-v2
- Reduce model size from 525MB to 87MB (83% reduction)
- Reduce embedding dimensions from 512 to 384 (faster distance calculations)
- Remove TensorFlow.js Float32Array patching (caused ONNX conflicts)
- Implement smart bundled model detection for offline operation
- Add explicit model download script for Docker deployments
- Remove complex environment variables in favor of simple configuration
- Update all distance functions to use optimized pure JavaScript
- Remove TensorFlow-specific utilities and type definitions

Performance Improvements:
- Model loading: 5x faster (87MB vs 525MB)
- Memory usage: 75% reduction (~200-400MB vs ~1.5GB)
- Distance calculations: Faster pure JS vs GPU overhead for small vectors
- Cold start performance: Significantly improved

Files Changed:
- Updated package.json: New dependencies, simplified scripts
- Rewrote src/utils/embedding.ts: Complete Transformers.js implementation
- Updated src/utils/distance.ts: Optimized JavaScript distance functions
- Simplified src/setup.ts: Removed TensorFlow-specific patching
- Simplified src/utils/textEncoding.ts: Only Node.js TextEncoder/Decoder patches
- Deleted src/utils/robustModelLoader.ts: TensorFlow-specific loader
- Deleted src/types/tensorflowTypes.ts: TensorFlow type definitions
- Added scripts/download-models.cjs: Docker-compatible model downloader
- Added comprehensive documentation: README.md, OFFLINE_MODELS.md, analysis docs

Testing:
- All 19 tests passing
- Removed test mocking in favor of real implementation testing
- Updated test environment for Transformers.js compatibility
- Performance tests validate improved efficiency

This migration resolves production issues with Docker egress limitations and provides a more robust, performant foundation for vector operations.

package.json

@@ -92,7 +92,8 @@
     "_workflow:minor": "node scripts/release-workflow.js minor",
     "_workflow:major": "node scripts/release-workflow.js major",
     "_workflow:dry-run": "npm run build && npm test && npm run _release:dry-run",
-    "_dry-run": "npm pack --dry-run"
+    "_dry-run": "npm pack --dry-run",
+    "download-models": "node scripts/download-models.cjs"
   },
   "keywords": [
     "vector-database",
@@ -128,7 +129,9 @@
     "!dist/framework.min.js.map",
     "LICENSE",
     "README.md",
-    "brainy.png"
+    "brainy.png",
+    "scripts/download-models.cjs",
+    "OFFLINE_MODELS.md"
   ],
   "devDependencies": {
     "@rollup/plugin-commonjs": "^25.0.7",
@@ -159,23 +162,11 @@
   },
   "dependencies": {
     "@aws-sdk/client-s3": "^3.540.0",
-    "@tensorflow/tfjs": "^4.22.0",
-    "@tensorflow/tfjs-backend-cpu": "^4.22.0",
-    "@tensorflow/tfjs-backend-webgl": "^4.22.0",
-    "@tensorflow/tfjs-converter": "^4.22.0",
-    "@tensorflow/tfjs-core": "^4.22.0",
+    "@huggingface/transformers": "^3.1.0",
     "buffer": "^6.0.3",
     "dotenv": "^16.4.5",
     "uuid": "^9.0.1"
   },
-  "peerDependencies": {
-    "@soulcraft/brainy-models": ">=0.7.0"
-  },
-  "peerDependenciesMeta": {
-    "@soulcraft/brainy-models": {
-      "optional": true
-    }
-  },
   "prettier": {
     "arrowParens": "always",
     "bracketSameLine": true,