Phase 3: individual defense assignments with invite codes

- progress V5 defense_sessions: per student+lab individual task (md), status
  machine waiting -> started -> ready, one-time 6-digit codes
- 30-min timer with server-side lazy expiry (syncTimeouts: started->ready by
  timeout), countdown JS on student page
- admin: assign task dialog (+prefill existing via data-md), CSV import
  (studentNo;task, \n for newlines) resolved via identity students,
  issue/reset code buttons, defense status column
- student: code entry form (code hidden until start), assignment md,
  'Готов к сдаче', waiting-for-teacher note
- gateway: /api/v1/defenses,/api/v1/defenses/** routes
- web api client + admin/student controllers wired

services/gateway/src/main/resources/application.yml

@@ -20,7 +20,7 @@ spring:
             - id: progress
               uri: ${LMS_PROGRESS_URI:http://localhost:8083}
               predicates:
-                - Path=/api/v1/assign,/api/v1/assign/**,/api/v1/assignments/**,/api/v1/levels,/api/v1/levels/**,/api/v1/me/**,/api/v1/distribute,/api/v1/distribute/**,/api/v1/grades,/api/v1/grades/**,/api/v1/submissions/**
+                - Path=/api/v1/assign,/api/v1/assign/**,/api/v1/defenses,/api/v1/defenses/**,/api/v1/assignments/**,/api/v1/levels,/api/v1/levels/**,/api/v1/me/**,/api/v1/distribute,/api/v1/distribute/**,/api/v1/grades,/api/v1/grades/**,/api/v1/submissions/**
 
 management:
   endpoints: