refactor(client): group pages by entity and add scenario/step crud

- move environment, scenario, session pages into entity subdirs
- add CreateScenarioPage and EditScenarioPage
- add CreateStepPage and EditStepPage with order/type/session/code fields
- add per-step edit and delete row actions on ScenarioDetailPage
- add step api methods (get, create, update, remove) to api client
- add sectionToolbar, formField, fieldLabel, textarea css utilities

client/src/i18n/locales/en.json

@@ -65,8 +65,7 @@
     "field_updated": "Updated",
     "field_lastUsed": "Last Used"
   },
-  "scenarios": {
-    "title": "Scenarios",
+  "scenarios": {    "title": "Scenarios",
     "col_id": "ID",
     "col_name": "Name",
     "col_updated": "Updated",
@@ -83,7 +82,17 @@
     "step_order": "#",
     "step_type": "Type",
     "step_session": "Session",
-    "step_updated": "Updated"
+    "step_updated": "Updated",
+    "action_add": "New scenario",
+    "action_edit": "Edit",
+    "action_save": "Create",
+    "action_update": "Save changes",
+    "action_cancel": "Cancel",
+    "create_title": "New Scenario",
+    "edit_title": "Edit Scenario",
+    "form_name": "Name",
+    "form_name_placeholder": "e.g. Login flow",
+    "form_name_required": "Name is required"
   },
   "theme": {
     "switch_to_light": "Switch to light theme",
@@ -97,5 +106,26 @@
     "range": "{{from}}–{{to}} of {{total}}",
     "per_page": "{{count}} per page",
     "page_size": "Items per page"
+  },
+  "steps": {
+    "create_title": "Add Step",
+    "edit_title": "Edit Step #{{order}}",
+    "loading": "Loading…",
+    "action_add": "Add step",
+    "action_edit": "Edit",
+    "action_delete": "Delete",
+    "action_save": "Add step",
+    "action_update": "Save changes",
+    "action_cancel": "Cancel",
+    "form_order": "Order",
+    "form_order_invalid": "Order must be a non-negative integer",
+    "form_type": "Type",
+    "form_session": "Session name",
+    "form_session_placeholder": "e.g. my-session",
+    "form_session_required": "Session name is required",
+    "form_exec_code": "Exec code",
+    "form_exec_code_placeholder": "return await page.title();",
+    "form_validate_code": "Validate code",
+    "form_validate_code_placeholder": "return { success: result !== null, description: \"…\" };"
   }
 }