feat(ideas): add idea creator, grant calls and applications

Implement the idea creator and application generator: idea status workflow, social canvas card, grant call windows with 409 when closed, and an LLM-backed idea assistant with offline fallback.

backend/Application/Dtos/ApplicationDtos.cs

@@ -0,0 +1,28 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace TarninaHub.Application.Dtos;
+
+public sealed record GrantCallResponse(
+    string Id,
+    string Name,
+    DateTimeOffset OpensAt,
+    DateTimeOffset ClosesAt,
+    string Status,
+    string? ExternalId);
+
+public sealed record CreateApplicationRequest(
+    [Required] string GrantCallId,
+    [Required] string IdeaId,
+    IReadOnlyDictionary<string, object?>? Content);
+
+public sealed record UpdateApplicationRequest(
+    IReadOnlyDictionary<string, object?>? Content,
+    string? Status);
+
+public sealed record ApplicationResponse(
+    string Id,
+    string GrantCallId,
+    string IdeaId,
+    IReadOnlyDictionary<string, object?> Content,
+    string Status,
+    DateTimeOffset CreatedAt);