refactor(securestore): store entire connection strings in SecureStore

Eliminates placeholder substitution (${KEY}) in favor of storing complete
connection strings as single encrypted values. SecureStore now auto-creates
entries for all connection strings defined in appsettings. ConfigManager
editor reads/writes values directly to SecureStore.

NEW/src/JdeScoping.Host/appsettings.json

@@ -1,9 +1,9 @@
 {
   "ConnectionStrings": {
-    "LotFinder": "Server=localhost,1434;Database=ScopingTool;User Id=scopingapp;Password=Sc0ping@pp_Dev#2024;TrustServerCertificate=true",
-    "JDE": "Data Source=jde-server:1521/JDEPROD;User Id=${JDE_USER};Password=${JDE_PASSWORD}",
-    "CMS": "Data Source=cms-server:1521/CMSPROD;User Id=${CMS_USER};Password=${CMS_PASSWORD}",
-    "GIW": "Data Source=giw-server:1521/GIWPROD;User Id=${GIW_USER};Password=${GIW_PASSWORD}"
+    "LotFinder": "",
+    "JDE": "",
+    "CMS": "",
+    "GIW": ""
   },
   "DataAccess": {
     "CommandTimeoutSeconds": 120,
@@ -54,13 +54,7 @@
     "RequiredKeys": [
       "RsaPrivateKey",
       "ExcelExport:CriteriaSheetPassword",
-      "ExcelExport:DataSheetPassword",
-      "JdeUser",
-      "JdePassword",
-      "GiwUser",
-      "GiwPassword",
-      "CmsUser",
-      "CmsPassword"
+      "ExcelExport:DataSheetPassword"
     ]
   },
   "WorkProcessor": {