refactor: complete migration from .env to YAML configuration

BREAKING CHANGE: Application now uses config.yaml instead of .env files

## Changes:
- Remove dotenv dependency from package.json
- Update all services to use ConfigManager for configuration
- Update tests to use fixed credentials instead of env vars
- Delete obsolete config-manager.test.ts (used old .env API)
- Update documentation (README.md, CLAUDE.md) to reflect new config system

## Configuration Architecture:
- ConfigManager: Centralized YAML configuration with Zod validation
- config.yaml location:
  - Development: Project root (easy to edit and version control)
  - Production: User AppData (persists across updates)
- ERP credentials: Stored in database (dbo_BIPUsers) per user
- Other settings: Stored in config.yaml (database, paths, extraction, etc.)

## Files Modified:
- package.json: Removed dotenv dependency
- cleaner-handler.ts: Use ConfigManager.getDatabaseType()
- run-migration.ts: Read from config.yaml instead of .env
- All integration tests: Use fixed test credentials
- tests/setup.ts: Removed dotenv loading
- README.md, CLAUDE.md: Updated documentation

Migration is complete. Application no longer depends on .env files.

tests/integration/cleaner.test.ts

@@ -6,10 +6,11 @@ import fs from 'fs/promises'
 import path from 'path'
 
 describe('Cleaner Service (Integration)', () => {
+  // For integration tests, use fixed test credentials or configure via config.yaml
   const config: ErpConfig = {
-    url: process.env.ERP_URL || '',
-    username: process.env.ERP_USERNAME || '',
-    password: process.env.ERP_PASSWORD || ''
+    url: '',
+    username: '',
+    password: ''
   }
 
   // Test data paths