feat(client): add ContextMenu component, environment cards, detail page, and breadcrumbs

- add ContextMenu component with click-outside/Escape dismiss, align prop, and danger variant
- replace EnvironmentsPage table with responsive card grid
- add cog button to each card opening a context menu with view and delete actions
- add EnvironmentDetailPage at /environments/:id with meta grid, URLs card, and delete
- add Breadcrumbs to all pages; detail page uses two-item trail with delete button inline
- add Table stories for pagination and Timestamp column

client/src/i18n/locales/en.json

@@ -11,7 +11,17 @@
     "col_name": "Name",
     "col_urls": "URLs",
     "col_updated": "Updated",
-    "empty": "No environments yet."
+    "empty": "No environments yet.",
+    "loading": "Loading…",
+    "no_urls": "No URLs configured.",
+    "menu_label": "Environment options",
+    "action_view": "View details",
+    "action_delete": "Delete",
+    "back": "Environments",
+    "field_id": "ID",
+    "field_created": "Created",
+    "field_updated": "Updated",
+    "section_urls": "URLs"
   },
   "keys": {
     "title": "Keys",