fix: add proper validation for empty shared configuration in SharePlugin

- Added validation to throw error when SharePlugin is initialized with empty shared config
- Fixed conflicting test expectation in SharePlugin.improved.test.ts to match validation behavior
- Ensures SharePlugin constructor throws descriptive error for invalid empty configurations

Fixes failing CI test: SharePlugin › constructor › should throw error for empty shared configuration

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

Co-Authored-By: Claude <[email protected]>

Author: ScriptedAlchemy

packages/enhanced/src/lib/sharing/SharePlugin.ts

@@ -108,6 +108,13 @@ class SharePlugin {
         },
       }));
 
+    // Validate that at least one shared module is configured
+    if (sharedOptions.length === 0) {
+      throw new Error(
+        'SharePlugin requires at least one shared module configuration',
+      );
+    }
+
     this._shareScope = options.shareScope || 'default';
     this._consumes = consumes;
     this._provides = provides;

packages/enhanced/test/unit/sharing/SharePlugin.improved.test.ts

@@ -287,14 +287,15 @@ describe('SharePlugin Real Behavior', () => {
   });
 
   describe('edge cases and error handling', () => {
-    it('should handle empty shared configuration', () => {
-      const plugin = new SharePlugin({
-        shareScope: 'default',
-        shared: {},
-      });
-
-      const compiler = createRealWebpackCompiler();
-      expect(() => plugin.apply(compiler)).not.toThrow();
+    it('should throw error for empty shared configuration', () => {
+      expect(() => {
+        new SharePlugin({
+          shareScope: 'default',
+          shared: {},
+        });
+      }).toThrow(
+        'SharePlugin requires at least one shared module configuration',
+      );
     });
 
     it('should handle missing shareScope with default fallback', () => {