refactor(scenario): remove step type and simplify scheduler to exec-only

- remove StepType, type column, and type field from step entity and DTOs
- remove executeLoginStep, executeSignStep, executeExecStep from scheduler
- inline exec logic directly in executeStepRun; all steps run execCode
- remove AuthService, EnvironmentService, runEnvironments from scheduler
- remove type selector from CreateStepPage and EditStepPage
- remove type badge column from ScenarioDetailPage
- fix useEffect dependency arrays in RunDetailPage (FINAL, id, runId, polling)
- fix duplicate /snippets proxy key in vite.config.ts
- remove unused escapeHtml export from hljs.ts

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

@@ -2,7 +2,6 @@ import { ApiProperty, ApiPropertyOptional } from "@nestjs/swagger";
 import { Type } from "class-transformer";
 import {
   IsArray,
-  IsIn,
   IsInt,
   IsNotEmpty,
   IsOptional,
@@ -11,7 +10,6 @@ import {
   Min,
   ValidateNested,
 } from "class-validator";
-import { StepType } from "../scenario-step.entity";
 
 export class ScenarioStepExportDto {
   @ApiProperty()
@@ -19,10 +17,6 @@ export class ScenarioStepExportDto {
   @Min(0)
   order: number;
 
-  @ApiProperty({ enum: ["login", "exec", "sign"] })
-  @IsIn(["login", "exec", "sign"])
-  type: StepType;
-
   @ApiPropertyOptional()
   @IsOptional()
   @IsString()