feat: Integrate @ruvector/attention as optional re-export from @ruvector/core

- Add @ruvector/attention as optional dependency
- Re-export attention module when installed
- Add VectorDB alias for compatibility
- Bump version to 0.1.16

Usage:
  const { VectorDB, attention } = require('@ruvector/core');
  const dpa = new attention.DotProductAttention(64);

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

npm/core/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@ruvector/core",
-  "version": "0.1.15",
+  "version": "0.1.16",
   "description": "High-performance Rust vector database for Node.js with HNSW indexing and SIMD optimizations",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
@@ -28,6 +28,9 @@
     "@types/node": "^20.19.25",
     "typescript": "^5.9.3"
   },
+  "optionalDependencies": {
+    "@ruvector/attention": "^0.1.0"
+  },
   "files": [
     "dist",
     "platforms",

npm/core/src/index.cjs.ts

@@ -89,11 +89,29 @@ function loadNativeBinding() {
 // Load the native module
 const nativeBinding = loadNativeBinding();
 
+// Try to load optional attention module
+let attention = null;
+try {
+  attention = require('@ruvector/attention');
+} catch {
+  // Attention module not installed - this is optional
+}
+
 // Export everything from the native binding
 module.exports = nativeBinding;
 
+// Add VectorDB alias (native exports as VectorDb)
+if (nativeBinding.VectorDb && !nativeBinding.VectorDB) {
+  module.exports.VectorDB = nativeBinding.VectorDb;
+}
+
 // Also export as default
 module.exports.default = nativeBinding;
 
 // Re-export DistanceMetric
 module.exports.DistanceMetric = DistanceMetric;
+
+// Export attention if available
+if (attention) {
+  module.exports.attention = attention;
+}

npm/core/src/index.ts

@@ -371,6 +371,17 @@ export const hello = nativeBinding.hello;
 export const getMetrics = nativeBinding.getMetrics;
 export const getHealth = nativeBinding.getHealth;
 
+// Try to load optional attention module
+let attention: any = null;
+try {
+  attention = require('@ruvector/attention');
+} catch {
+  // Attention module not installed - this is optional
+}
+
+// Export attention if available
+export { attention };
+
 // Default export
 export default {
   VectorDB,
@@ -379,5 +390,7 @@ export default {
   hello,
   getMetrics,
   getHealth,
-  DistanceMetric
+  DistanceMetric,
+  // Include attention if available
+  ...(attention ? { attention } : {})
 };