Add optional learningMaterial field to ChallengeTask model for additional educational content; update API endpoints, TypeScript interfaces, and frontend forms to support this feature. Enhance localization for English and Russian to include new field descriptions and placeholders.

src/types/challenge.ts

@@ -12,6 +12,7 @@ export interface ChallengeTask {
   id: string
   title: string
   description: string // Markdown
+  learningMaterial?: string // Дополнительный учебный материал в Markdown
   hiddenInstructions?: string // Только для преподавателей
   creator?: {
     sub: string
@@ -121,12 +122,14 @@ export interface APIResponse<T> {
 export interface CreateTaskRequest {
   title: string
   description: string
+  learningMaterial?: string
   hiddenInstructions?: string
 }
 
 export interface UpdateTaskRequest {
   title?: string
   description?: string
+  learningMaterial?: string
   hiddenInstructions?: string
 }