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/sql-server.test.ts

@@ -9,12 +9,13 @@ import { SqlServerService, SqlServerConfig } from '@main/services/database/sql-s
 import * as sql from 'mssql'
 
 // SQL Server test configuration
+// For integration tests, use fixed test credentials or configure via config.yaml
 const testConfig: SqlServerConfig = {
-  server: process.env.SQL_SERVER_HOST || 'localhost',
-  port: parseInt(process.env.SQL_SERVER_PORT || '1433'),
-  user: process.env.SQL_SERVER_USER || 'sa',
-  password: process.env.SQL_SERVER_PASSWORD || 'password',
-  database: process.env.SQL_SERVER_DATABASE || 'testdb',
+  server: 'localhost',
+  port: 1433,
+  user: 'sa',
+  password: 'password',
+  database: 'testdb',
   options: {
     encrypt: false, // Set to true for Azure SQL
     trustServerCertificate: true // Set to false in production with valid cert