feat: add core persistence model

Tiku.Domain/QuestionBanks/QuestionEntities.cs

@@ -0,0 +1,71 @@
+using System.Text.Json;
+using Tiku.Domain.Common;
+
+namespace Tiku.Domain.QuestionBanks;
+
+public sealed class QuestionBank : AuditableTenantEntity
+{
+    public Guid? RegionId { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public QuestionBankScope SourceScope { get; set; } = QuestionBankScope.Tenant;
+    public QuestionBankStatus Status { get; set; } = QuestionBankStatus.Active;
+    public JsonElement Metadata { get; set; } = JsonDefaults.Object();
+}
+
+public enum QuestionBankScope
+{
+    Platform,
+    Tenant
+}
+
+public enum QuestionBankStatus
+{
+    Active,
+    Archived
+}
+
+public sealed class Question : AuditableTenantEntity
+{
+    public Guid? QuestionBankId { get; set; }
+    public Guid? SubjectId { get; set; }
+    public Guid? CategoryId { get; set; }
+    public Guid? NodeId { get; set; }
+    public string? LegacyId { get; set; }
+    public string? LegacySubjectId { get; set; }
+    public string? LegacyCategoryId { get; set; }
+    public string? LegacyNodeId { get; set; }
+    public string Type { get; set; } = "choice";
+    public string? TypeLabel { get; set; }
+    public int? Difficulty { get; set; }
+    public JsonElement Tags { get; set; } = JsonDefaults.Array();
+    public string? MediaUrl { get; set; }
+    public bool HasVideoExplanation { get; set; }
+    public QuestionStatus Status { get; set; } = QuestionStatus.Published;
+    public Guid? CurrentVersionId { get; set; }
+}
+
+public enum QuestionStatus
+{
+    Draft,
+    Published,
+    Archived
+}
+
+public sealed class QuestionVersion : Entity
+{
+    public Guid TenantId { get; set; }
+    public Guid QuestionId { get; set; }
+    public int VersionNo { get; set; } = 1;
+    public string? Content { get; set; }
+    public JsonElement Options { get; set; } = JsonDefaults.Array();
+    public int? CorrectOptionIndex { get; set; }
+    public JsonElement CorrectOptionIndices { get; set; } = JsonDefaults.Array();
+    public string? AnswerText { get; set; }
+    public string? Explanation { get; set; }
+    public JsonElement SubQuestions { get; set; } = JsonDefaults.Array();
+    public string? CodeLang { get; set; }
+    public string? CodeTemplate { get; set; }
+    public string? SourceHash { get; set; }
+    public Guid? CreatedBy { get; set; }
+    public DateTimeOffset CreatedAt { get; set; } = DateTimeOffset.UtcNow;
+}