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/browser.controller.spec.ts

@@ -136,35 +136,35 @@ describe("BrowserController", () => {
       expect(res.body).toEqual({ result: 42 });
     });
 
-    it("exposes environment via helpers.env in a named session", async () => {
+    it("exposes environment via context.env in a named session", async () => {
       const res = await request(app.getHttpServer())
         .post("/exec")
         .send({
           sessionName: "no-such-session",
-          code: "return helpers.env.BASE_URL;",
+          code: "return context.env.BASE_URL;",
           environment: { BASE_URL: "https://env.example.com" },
         })
         .expect(201);
       expect(res.body).toEqual({ result: "https://env.example.com" });
     });
 
-    it("exposes environment via helpers.env in a sessionless exec", async () => {
+    it("exposes environment via context.env in a sessionless exec", async () => {
       const res = await request(app.getHttpServer())
         .post("/exec")
         .send({
-          code: "return helpers.env.KEY;",
+          code: "return context.env.KEY;",
           environment: { KEY: "value123" },
         })
         .expect(201);
       expect(res.body).toEqual({ result: "value123" });
     });
 
-    it("exposes credentials via helpers.getCredential in a named session", async () => {
+    it("exposes credentials via context.getCredential in a named session", async () => {
       const res = await request(app.getHttpServer())
         .post("/exec")
         .send({
           sessionName: "no-such-session",
-          code: "return helpers.getCredential('admin');",
+          code: "return context.getCredential('admin');",
           credentials: { admin: { username: "user1", password: "pass1" } },
         })
         .expect(201);
@@ -173,11 +173,11 @@ describe("BrowserController", () => {
       });
     });
 
-    it("exposes credentials via helpers.getCredential in a sessionless exec", async () => {
+    it("exposes credentials via context.getCredential in a sessionless exec", async () => {
       const res = await request(app.getHttpServer())
         .post("/exec")
         .send({
-          code: "return helpers.getCredential('svc');",
+          code: "return context.getCredential('svc');",
           credentials: { svc: { token: "abc" } },
         })
         .expect(201);
@@ -188,7 +188,7 @@ describe("BrowserController", () => {
       const res = await request(app.getHttpServer())
         .post("/exec")
         .send({
-          code: "return helpers.getCredential('missing');",
+          code: "return context.getCredential('missing');",
           credentials: {},
         })
         .expect(500);
@@ -199,7 +199,7 @@ describe("BrowserController", () => {
       const res = await request(app.getHttpServer())
         .post("/exec")
         .send({
-          code: "return Object.keys(helpers.env).length === 0 ? 'empty' : 'not-empty';",
+          code: "return Object.keys(context.env).length === 0 ? 'empty' : 'not-empty';",
         })
         .expect(201);
       expect(res.body).toEqual({ result: "empty" });