v1.3.0 Restructure Saxonite workspace and upgrade to .NET 10 (#1)

Move Saxonite’s projects into a dedicated `Workspace` folder and align the solution with .NET 10 and the current Common workspace. Update encryption integration, test project structure and coverage, and repository guidance and upgrade notes.

- Relocate application and library projects while retaining Git rename history.
- Split tests into Admin, Online, and Shared projects; add representative behavioral and serialization tests.
- Update Common integration, application version, and repository documentation.

Application version: 1.3.0

Reviewed-on: #1
Co-authored-by: andy <andy@sarand.com>

Workspace/SaxoniteCoreWebAdmin/appsettings.Development.json

@@ -0,0 +1,26 @@
+{
+    "Logging": {
+        "LogLevel": {
+            "Default": "Information",
+            "Microsoft": "Warning",
+            "Microsoft.Hosting.Lifetime": "Information"
+        }
+    },
+    "EmailConfigs": {
+        "SAX-SF-Dev": {
+            "Message": {
+                "AddressFrom": "DoNotReply@sportierre.com"
+            },
+            "SMTP": {
+                "Server": "smtp.ionos.co.uk",
+                "ServerPort": 587,
+                "UseSSL": true
+            },
+            "Send": {
+                "Using": 2,
+                "UserName": "info@sportierre.com",
+                "Password": "5p0rTi3rre-info-2021!"
+            }
+        }
+    }
+}