feat(backend): add JWT authentication, RBAC and consent/audit services

Add signup/signin with backend-issued JWT (Argon2 passwords in SurrealDB), role-based authorization policies, per-user data access levels, consent register and read audit log. Protect user endpoints and record sensitive reads.

backend/Application/Mappings/UserMappings.cs

@@ -0,0 +1,14 @@
+using TarninaHub.Application.Dtos;
+using TarninaHub.Application.Models;
+
+namespace TarninaHub.Application.Mappings;
+
+public static class UserMappings
+{
+    public static UserResponse ToResponse(this UserAccount user) => new(
+        user.Id,
+        user.Phone,
+        user.Email,
+        user.Role,
+        user.OrganizationId);
+}