feat(scenarios): add step title, scenario credentials, and environment context in executor

- add nullable title column to scenario steps; exposed in create/edit forms and step table
- add scenario-credential join (many-to-many with CredentialEntity) with CRUD endpoints
- expose environment URLs in code executor helpers via helpers.env and helpers.getEnvUrl()
- resolve and cache environment per run from the login step's environmentName in scheduler
- add section spacing and step table title column to ScenarioDetailPage

client/src/api/client.ts

@@ -1,7 +1,9 @@
 import type {
   PaginatedResponse,
+  Credential,
   Environment,
   KeysResponse,
+  ScenarioCredential,
   Session,
   Scenario,
   ScenarioRun,
@@ -30,6 +32,32 @@ async function request<T>(path: string, init?: RequestInit): Promise<T> {
   return JSON.parse(text) as T;
 }
 
+// ── Credentials ───────────────────────────────────────────────────────────────
+
+export const credentials = {
+  list(page = 1, limit = 50): Promise<PaginatedResponse<Credential>> {
+    return request(`/credentials?page=${page}&limit=${limit}`);
+  },
+  get(id: number): Promise<Credential> {
+    return request(`/credentials/${id}`);
+  },
+  create(name: string, data?: string): Promise<Credential> {
+    return request('/credentials', {
+      method: 'POST',
+      body: JSON.stringify({ name, data }),
+    });
+  },
+  update(id: number, patch: Partial<Pick<Credential, 'name' | 'data'>>): Promise<Credential> {
+    return request(`/credentials/${id}`, {
+      method: 'PATCH',
+      body: JSON.stringify(patch),
+    });
+  },
+  remove(id: number): Promise<void> {
+    return request(`/credentials/${id}`, { method: 'DELETE' });
+  },
+};
+
 // ── Environments ──────────────────────────────────────────────────────────────
 
 export const environments = {
@@ -132,9 +160,28 @@ export const runs = {
   },
 };
 
-// ── Scenario Steps ────────────────────────────────────────────────────────────
+// ── Scenario Credentials ──────────────────────────────────────────────────────
 
+export const scenarioCredentials = {
+  list(scenarioId: number): Promise<ScenarioCredential[]> {
+    return request(`/scenarios/${scenarioId}/credentials`);
+  },
+  add(scenarioId: number, credentialId: number, alias: string): Promise<ScenarioCredential> {
+    return request(`/scenarios/${scenarioId}/credentials`, {
+      method: 'POST',
+      body: JSON.stringify({ credentialId, alias }),
+    });
+  },
+  remove(scenarioId: number, scCredId: number): Promise<void> {
+    return request(`/scenarios/${scenarioId}/credentials/${scCredId}`, {
+      method: 'DELETE',
+    });
+  },
+};
+
+// ── Scenario Steps ────────────────────────────────────────────────────────────
 export interface CreateStepPayload {
+  title?: string;
   order: number;
   type: 'login' | 'exec' | 'sign';
   sessionName: string;
@@ -143,6 +190,7 @@ export interface CreateStepPayload {
 }
 
 export interface UpdateStepPayload {
+  title?: string;
   order?: number;
   type?: 'login' | 'exec' | 'sign';
   sessionName?: string;