feat: implement configuration management system

- Add comprehensive TypeScript interfaces for all config types
- Implement ConfigManager singleton class with layered loading
- Support for default, environment-specific, and environment variable configs
- Add example .env file for sensitive configuration

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

config/app.json

@@ -8,8 +8,8 @@
     "timeout": 30000
   },
   "erp": {
-    "baseUrl": "https://68.11.34.30:8082",
-    "ignoreHttpsErrors": true
+    "baseUrl": "",
+    "ignoreHttpsErrors": false
   },
   "paths": {
     "tempDir": "./data/temp",