refactor(code-executor): migrate user scripts to single context argument

- replace (page, context, helpers) signature with async (context) => {}
- add ScriptContext interface exposing page, browser, env, getEnv,
  getCredential, getStepOutput, runSnippet, dumpDom, log/warn/error
- rename getEnvUrl to getEnv throughout service and docs
- fix step ordering: normalizeStepOrder and run step rows are now 1-based
- migrate existing DB rows (scenario_steps, scenario_run_steps) +1
- update all tests and stored snippet/step code in DB to new API

server/src/scenario/scenario-scheduler.service.ts

@@ -72,7 +72,7 @@ export class ScenarioSchedulerService {
   ): (order: number) => Promise<unknown> {
     return async (order: number) => {
       const targetOrder = order < 0 ? stepRun.order + order : order;
-      if (targetOrder < 0) return null;
+      if (targetOrder < 1) return null;
       const sr = await this.runStepRepo.findOne({
         where: { runId: stepRun.runId, order: targetOrder },
       });
@@ -172,16 +172,16 @@ export class ScenarioSchedulerService {
       const creds = this.runCredentials.get(stepRun.runId);
       const snips = this.runSnippets.get(stepRun.runId);
       const env = this.runEnvironments.get(stepRun.runId);
-      const { result: execOutput } = await this.codeExecutor.execute(
+      const { result: execOutput } = await this.codeExecutor.execute({
         page,
-        context,
-        step.execCode,
-        this.stepLogger(stepRun.id, stepRun.runId),
+        browser: context,
+        code: step.execCode,
+        log: this.stepLogger(stepRun.id, stepRun.runId),
         getStepOutput,
-        creds,
-        env,
-        snips,
-      );
+        credentials: creds,
+        environment: env,
+        snippets: snips,
+      });
 
       await this.passStepRun(stepRun, null, execOutput);
     } catch (err) {