Harden request validation and admin UX cues

Backend/Endpoints/PublicEndpointSupport.cs

@@ -1,4 +1,5 @@
 using Backend.Common;
+using Backend.Contracts;
 using Backend.Domain;
 using Backend.Services;
 using Microsoft.AspNetCore.Http.Extensions;
@@ -205,4 +206,74 @@ public static partial class PublicEndpoints
             "show" => "show",
             _ => "current",
         };
+
+    private static IResult? ValidateCreateNominationRequest(CreateNominationRequest? request)
+    {
+        if (request is null)
+        {
+            return Results.BadRequest(new { message = "A nomination request body is required." });
+        }
+
+        if (request.Year <= 0)
+        {
+            return Results.BadRequest(new { message = "A valid season year is required." });
+        }
+
+        if ((request.Nominations?.Length ?? 0) == 0 && (request.Nominees?.Length ?? 0) == 0)
+        {
+            return Results.BadRequest(new { message = "A nomination request must include at least one stream link." });
+        }
+
+        return null;
+    }
+
+    private static IResult? ValidateCreateVoteRequest(CreateVoteRequest? request)
+    {
+        if (request is null)
+        {
+            return Results.BadRequest(new { message = "A vote request body is required." });
+        }
+
+        if (request.SeasonId <= 0)
+        {
+            return Results.BadRequest(new { message = "A valid season id is required." });
+        }
+
+        if (request.Entries is null || request.Entries.Length == 0)
+        {
+            return Results.BadRequest(new { message = "At least one vote entry is required." });
+        }
+
+        if (request.Entries.Any(item => item.CategoryId <= 0 || item.CandidateId <= 0))
+        {
+            return Results.BadRequest(new { message = "Each vote entry requires a valid category and candidate." });
+        }
+
+        return null;
+    }
+
+    private static IResult? ValidateCreateClipRequest(CreateClipRequest? request)
+    {
+        if (request is null)
+        {
+            return Results.BadRequest(new { message = "A clip request body is required." });
+        }
+
+        if (request.Year <= 0)
+        {
+            return Results.BadRequest(new { message = "A valid season year is required." });
+        }
+
+        if (request.CategoryId is <= 0 || request.CandidateId is <= 0)
+        {
+            return Results.BadRequest(new { message = "Category and candidate ids must be positive when provided." });
+        }
+
+        if (string.IsNullOrWhiteSpace(request.ClipUrl))
+        {
+            return Results.BadRequest(new { message = "A valid http(s) clip link is required." });
+        }
+
+        return null;
+    }
 }