refactor: rename email-server-worker to email-worker

Rename directory from email-server-worker to email-worker for clarity and brevity. Update all references in CLAUDE.md documentation.

email-worker/.vscode/settings.json

@@ -0,0 +1,10 @@
+{
+    "jest.jestCommandLine": "npm run test --",
+    "jest.autoRun": {
+        "watch": false,
+        "onSave": "test-file"
+    },
+    "jest.nodeEnv": {
+        
+    }
+}