feat: enforce tenant isolation and shared question bank

Tiku.Application/Tenancy/TenantFrontendConfigModels.cs

@@ -0,0 +1,47 @@
+using System.Text.Json;
+
+namespace Tiku.Application.Tenancy;
+
+public sealed record TenantFrontendConfigDraft(
+    JsonElement Branding,
+    JsonElement Theme,
+    JsonElement Features,
+    JsonElement Navigation,
+    JsonElement HomeModules);
+
+public sealed record TenantFrontendConfigItem(
+    int SchemaVersion,
+    int ConfigVersion,
+    TenantFrontendConfigDraft Published,
+    TenantFrontendConfigDraft Draft,
+    DateTimeOffset? PublishedAt);
+
+public sealed record TenantRuntimeBootstrap(
+    int SchemaVersion,
+    int ConfigVersion,
+    string TenantCode,
+    string TenantName,
+    JsonElement Branding,
+    JsonElement Theme,
+    JsonElement Features,
+    JsonElement Navigation,
+    JsonElement HomeModules);
+
+public interface ITenantFrontendConfigService
+{
+    Task<TenantFrontendConfigItem> GetAsync(Guid tenantId, CancellationToken cancellationToken = default);
+    Task<TenantFrontendConfigItem> SaveDraftAsync(
+        Guid tenantId,
+        TenantFrontendConfigDraft draft,
+        CancellationToken cancellationToken = default);
+    Task<TenantFrontendConfigItem> PublishAsync(
+        Guid tenantId,
+        int expectedVersion,
+        CancellationToken cancellationToken = default);
+    Task<TenantRuntimeBootstrap> GetRuntimeAsync(Guid tenantId, CancellationToken cancellationToken = default);
+}
+
+public sealed class TenantFrontendConfigException(string code, string message) : Exception(message)
+{
+    public string Code { get; } = code;
+}