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/Infrastructure/Persistence/KnowledgeItemRow.cs

@@ -0,0 +1,23 @@
+using Dahomey.Cbor.Attributes;
+
+namespace TarninaHub.Infrastructure.Persistence;
+
+
+internal sealed class KnowledgeItemRow
+{
+    [CborProperty("id")] public string Id { get; set; } = string.Empty;
+
+    [CborProperty("title")] public string Title { get; set; } = string.Empty;
+
+    [CborProperty("kind")] public string Kind { get; set; } = string.Empty;
+
+    [CborProperty("challenge")] public string? Challenge { get; set; }
+
+    [CborProperty("source_url")] public string? SourceUrl { get; set; }
+
+    [CborProperty("attachments")] public List<Dictionary<string, string?>> Attachments { get; set; } = [];
+
+    [CborProperty("published")] public bool Published { get; set; }
+
+    [CborProperty("updated_at")] public DateTimeOffset? UpdatedAt { get; set; }
+}