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/test/scenario-step-output.spec.ts

@@ -1,6 +1,6 @@
 /**
  * Integration tests for ScenarioRunStepEntity.output column and the
- * helpers.getStepOutput() API available inside exec step scripts.
+ * context.getStepOutput() API available inside exec step scripts.
  *
  * Strategy:
  * - Seed a session row so the scheduler can create a browser context.
@@ -17,7 +17,7 @@ import { ScenarioService } from "../src/scenario/scenario.service";
 import { ScenarioSchedulerService } from "../src/scenario/scenario-scheduler.service";
 import { EnvironmentEntity } from "../src/environment/environment.entity";
 
-describe("ScenarioRunStepEntity.output + helpers.getStepOutput", () => {
+describe("ScenarioRunStepEntity.output + context.getStepOutput", () => {
   let app: INestApplication;
   let dataSource: DataSource;
   let scenarioService: ScenarioService;
@@ -135,15 +135,15 @@ describe("ScenarioRunStepEntity.output + helpers.getStepOutput", () => {
     });
   });
 
-  // ── helpers.getStepOutput ──────────────────────────────────────────────────
+  // ── context.getStepOutput ──────────────────────────────────────────────────
 
-  describe("helpers.getStepOutput()", () => {
+  describe("context.getStepOutput()", () => {
     it("returns output of a previous step by absolute order", async () => {
       await seedSession();
       const scId = await createScenario("getStepOutput-absolute");
       await createStep(scId, 0, "return 99;");
-      // Step 1 reads step 0's output via absolute index 0
-      await createStep(scId, 1, "return await helpers.getStepOutput(0);");
+      // Step 1 reads step 1's output via absolute index 1 (1-based)
+      await createStep(scId, 1, "return await context.getStepOutput(1);");
 
       const runId = await runScenario(scId);
       const rows = await dataSource.query(
@@ -159,7 +159,7 @@ describe("ScenarioRunStepEntity.output + helpers.getStepOutput", () => {
       const scId = await createScenario("getStepOutput-relative");
       await createStep(scId, 0, 'return "step-zero";');
       // Step 1 uses relative index -1 to reference step 0
-      await createStep(scId, 1, "return await helpers.getStepOutput(-1);");
+      await createStep(scId, 1, "return await context.getStepOutput(-1);");
 
       const runId = await runScenario(scId);
       const rows = await dataSource.query(
@@ -173,7 +173,7 @@ describe("ScenarioRunStepEntity.output + helpers.getStepOutput", () => {
       await seedSession();
       const scId = await createScenario("getStepOutput-missing");
       // Step 0 tries to read step order 99 which does not exist
-      await createStep(scId, 0, "return await helpers.getStepOutput(99);");
+      await createStep(scId, 0, "return await context.getStepOutput(99);");
 
       const runId = await runScenario(scId);
       const row = await dataSource.query(
@@ -190,12 +190,12 @@ describe("ScenarioRunStepEntity.output + helpers.getStepOutput", () => {
       await createStep(
         scId,
         1,
-        "const prev = await helpers.getStepOutput(-1); return [...prev, 3];",
+        "const prev = await context.getStepOutput(-1); return [...prev, 3];",
       );
       await createStep(
         scId,
         2,
-        "const prev = await helpers.getStepOutput(-1); return [...prev, 4];",
+        "const prev = await context.getStepOutput(-1); return [...prev, 4];",
       );
 
       const runId = await runScenario(scId);