chore: add development configuration files

Add .env with default development settings and .vscode debug configurations for easier local development.

- .env: Development environment variables (PORT, DEBUG, PULL_INTERVAL)
- .vscode/launch.json: Debug configurations for server and Jest tests
- .vscode/settings.json: Jest integration settings

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

email-server-worker/.vscode/settings.json

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