feat(backend): add support conversations

Foxnouns.Backend/Utils/AuthUtils.cs

@@ -7,6 +7,7 @@ public static class AuthUtils
 {
     public const string ClientCredentials = "client_credentials";
     public const string AuthorizationCode = "authorization_code";
+
     private static readonly string[] ForbiddenSchemes =
     [
         "javascript",
@@ -21,6 +22,7 @@ public static class AuthUtils
         "user.read_hidden",
         "user.read_privileged",
         "user.update",
+        "user.support",
     ];
 
     public static readonly string[] MemberScopes =

Foxnouns.Backend/Utils/ValidationUtils.cs

@@ -9,6 +9,25 @@ namespace Foxnouns.Backend.Utils;
 /// </summary>
 public static partial class ValidationUtils
 {
+    public static void ValidateStringLength(
+        this string s,
+        string fieldName,
+        int minLength,
+        int maxLength
+    )
+    {
+        if (s.Length < minLength)
+            throw new ApiError.BadRequest(
+                fieldName,
+                ValidationError.LengthError("Field is too short", minLength, maxLength, s.Length)
+            );
+        if (s.Length > maxLength)
+            throw new ApiError.BadRequest(
+                fieldName,
+                ValidationError.LengthError("Field is too long", minLength, maxLength, s.Length)
+            );
+    }
+
     private static readonly string[] InvalidUsernames =
     [
         "..",