refactor: address code review findings across all projects

Apply comprehensive fixes from code reviews including:
- Extract shared utilities (SqlFormatHelper, CellValueConverter, DbDestinationBase)
- Add interface abstractions (IAuthenticationService, IDatabaseMigrator, IMisQueryBuilder)
- Implement SecureStore for encrypted secrets storage
- Fix error handling with proper HTTP status codes and logging
- Optimize double enumeration in DevEtlRegistry
- Add DataSync.Dev README for developer onboarding
- Extract filter panel base classes to reduce duplication
- Update code review docs to mark all issues as fixed

NEW/src/JdeScoping.Host/appsettings.json

@@ -128,6 +128,13 @@
     "UseFileDataSource": false,
     "FileDirectory": "DevData"
   },
+  "SecureStore": {
+    "StorePath": "data/secrets.json",
+    "KeyFilePath": "data/secrets.key",
+    "MasterKeyEnvVar": "SCOPINGTOOL_MASTER_KEY",
+    "AutoCreateStore": true,
+    "MigrateExistingSecrets": true
+  },
   "WorkProcessor": {
     "Enabled": true,
     "WorkInterval": "00:00:05",