Initial commit: standalone quiz-testing system

Full-stack F# (Domain/Server/Client via Fable+Elmish+Feliz), PostgreSQL
persistence via Dapper, Docker Compose deployment. Student quiz-taking flow
with time-limit enforcement and focus-loss tracking, Teacher question bank
and quiz builder with results analytics, Admin user management.

src/Server/Features/Teacher/DeleteQuiz.fs

@@ -0,0 +1,27 @@
+module Server.Features.Teacher.DeleteQuiz
+
+open Giraffe
+open Domain
+open Domain.Contracts
+open Server.Store
+
+let private delete (store: Store) (ownerId: UserId) (req: DeleteQuizRequest) : Result<unit, string> =
+    match store.TryGetQuiz req.QuizId with
+    | None -> Error "Тест не найден"
+    | Some quiz when quiz.OwnerId <> ownerId -> Error "Доступ запрещён"
+    | Some _ ->
+        if store.AnyAttemptsForQuiz req.QuizId then
+            Error "Тест уже проходили, удаление невозможно"
+        else
+            store.RemoveQuiz req.QuizId
+            Ok()
+
+let handler (store: Store) : HttpHandler =
+    bindJson<DeleteQuizRequest> (fun req next ctx ->
+        task {
+            let result =
+                Server.Auth.requireRole [ Teacher; Admin ] ctx.User
+                |> Result.bind (fun uid -> delete store uid req)
+
+            return! json result next ctx
+        })