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/KnowledgeItemService.cs

@@ -62,7 +62,7 @@ public sealed class KnowledgeItemService : IKnowledgeItemService
             ["id"] = id,
             ["title"] = request.Title,
             ["kind"] = request.Kind,
-            ["attachments"] = request.Attachments ?? [],
+            ["attachments"] = ToConcreteList(request.Attachments),
             ["published"] = request.Published,
         };
 
@@ -99,7 +99,7 @@ public sealed class KnowledgeItemService : IKnowledgeItemService
             ["id"] = id,
             ["title"] = request.Title,
             ["kind"] = request.Kind,
-            ["attachments"] = request.Attachments ?? [],
+            ["attachments"] = ToConcreteList(request.Attachments),
             ["published"] = request.Published,
         };
 
@@ -216,13 +216,17 @@ public sealed class KnowledgeItemService : IKnowledgeItemService
         }
     }
 
+    private static List<Dictionary<string, string?>> ToConcreteList(
+        IReadOnlyList<IReadOnlyDictionary<string, string?>>? values) =>
+        values?.Select(item => item.ToDictionary(pair => pair.Key, pair => pair.Value)).ToList() ?? [];
+
     private static KnowledgeItemResponse Map(KnowledgeItemRow row) => new(
         row.Id,
         row.Title,
         row.Kind,
         NormalizeRecordId(row.Challenge),
         row.SourceUrl,
-        row.Attachments.Select(item => (IReadOnlyDictionary<string, object?>)item).ToList(),
+        row.Attachments.Select(item => (IReadOnlyDictionary<string, string?>)item).ToList(),
         row.Published,
         row.UpdatedAt);