feat(scenarios): add detail page, comfortable DescriptionList layout, and environment card refactor

- Add ScenarioDetailPage with DescriptionList, steps table, run/delete actions
- Add /scenarios/:id route
- Add i18n keys for scenario detail fields, steps columns, and 404 error
- Add 'comfortable' and 'inline' layout variants to DescriptionList (with compact as default stacked)
- Apply layout="comfortable" to session, environment, and scenario detail pages
- Apply layout="compact" to EnvironmentsPage card DescriptionList
- Refactor EnvironmentsPage card to use ContextMenu (view/edit/delete) with icons
- Add ScenariosPage clickable rows, Play icon (primary) and Trash2 icon (danger) action buttons
- Add Page.module.css sectionHeading and stepsSection utility classes
- Fix Notification.tsx and Table.tsx formatting (prettier)

client/src/i18n/locales/en.json

@@ -3,6 +3,7 @@
     "not_found": "Not found",
     "not_found_session": "Session {{id}} does not exist or has been deleted.",
     "not_found_environment": "Environment {{id}} does not exist or has been deleted.",
+    "not_found_scenario": "Scenario {{id}} does not exist or has been deleted.",
     "generic": "Something went wrong. Please try again."
   },
   "nav": {
@@ -70,8 +71,19 @@
     "col_name": "Name",
     "col_updated": "Updated",
     "empty": "No scenarios yet.",
+    "loading": "Loading…",
     "action_run": "Run",
-    "action_delete": "Delete"
+    "action_delete": "Delete",
+    "field_id": "ID",
+    "field_name": "Name",
+    "field_steps": "Steps",
+    "field_created": "Created",
+    "field_updated": "Updated",
+    "steps_heading": "Steps",
+    "step_order": "#",
+    "step_type": "Type",
+    "step_session": "Session",
+    "step_updated": "Updated"
   },
   "theme": {
     "switch_to_light": "Switch to light theme",