feat(scenarios,environments): add markdown description field

- add optional description to scenario and environment entities
- expose description in create/update DTOs, MCP tools, and export DTOs
- render description as markdown on detail pages
- add description editor (CodeEditor) to create/edit forms for both resources

server/src/scenario/dto/create-scenario.dto.ts

@@ -1,9 +1,14 @@
-import { ApiProperty } from "@nestjs/swagger";
-import { IsNotEmpty, IsString } from "class-validator";
+import { ApiProperty, ApiPropertyOptional } from "@nestjs/swagger";
+import { IsNotEmpty, IsOptional, IsString } from "class-validator";
 
 export class CreateScenarioDto {
   @ApiProperty({ example: "Login and verify cabinet" })
   @IsString()
   @IsNotEmpty()
   name: string;
+
+  @ApiPropertyOptional({ description: "Optional markdown description" })
+  @IsOptional()
+  @IsString()
+  description?: string;
 }