Phase 0 WP-0.2–0.9: Implement Commons (types, entities, interfaces, messages, protocol, tests)

- WP-0.2: Namespace/folder skeleton (26 directories)
- WP-0.3: Shared data types (6 enums, RetryPolicy, Result<T>)
- WP-0.4: 24 domain entity POCOs across 10 domain areas
- WP-0.5: 7 repository interfaces with full CRUD signatures
- WP-0.6: IAuditService cross-cutting interface
- WP-0.7: 26 message contract records across 8 concern areas
- WP-0.8: IDataConnection protocol abstraction with batch ops
- WP-0.9: 8 architectural constraint enforcement tests
All 40 tests pass, zero warnings.

src/ScadaLink.Commons/Entities/Security/LdapGroupMapping.cs

@@ -0,0 +1,14 @@
+namespace ScadaLink.Commons.Entities.Security;
+
+public class LdapGroupMapping
+{
+    public int Id { get; set; }
+    public string LdapGroupName { get; set; }
+    public string Role { get; set; }
+
+    public LdapGroupMapping(string ldapGroupName, string role)
+    {
+        LdapGroupName = ldapGroupName ?? throw new ArgumentNullException(nameof(ldapGroupName));
+        Role = role ?? throw new ArgumentNullException(nameof(role));
+    }
+}

src/ScadaLink.Commons/Entities/Security/SiteScopeRule.cs

@@ -0,0 +1,8 @@
+namespace ScadaLink.Commons.Entities.Security;
+
+public class SiteScopeRule
+{
+    public int Id { get; set; }
+    public int LdapGroupMappingId { get; set; }
+    public int SiteId { get; set; }
+}