feat(backend): add communication, tester, admin and middleman modules

Implement step 17 modules: threads/messages, notifications with automation (submission.created, idea.created, grant_call.opened), innovation test feedback, admin panel (submissions, verify, metrics, grant call status), Middleman adaptation and partnerships. Split multi-type files into one type per file and replace object-valued dictionaries with string-valued maps in data contracts (migrations 0006/0007).

backend/Application/Security/RoleNames.cs

@@ -0,0 +1,16 @@
+namespace TarninaHub.Application.Security;
+
+
+public static class RoleNames
+{
+    public const string User = "user";
+    public const string Jst = "jst";
+    public const string Operator = "operator";
+    public const string Manager = "manager";
+    public const string Admin = "admin";
+
+    public static readonly IReadOnlyList<string> All =
+        [User, Jst, Operator, Manager, Admin];
+
+    public static bool IsValid(string role) => All.Contains(role);
+}