feat(client): add UI kit, data layer, app shell, and Table component

- design token system (Atlantis, Kimberly, Powder Ash palette)
- Button, Badge, Input, Select, Card, SidePanel, Breadcrumbs components
- generic typed Table<T> component with loading/empty states
- API data layer: typed fetch client for environments, keys, sessions, scenarios
- Vite dev proxy targeting server on port 13000
- App shell with SidePanel nav and four entity pages (Environments, Keys, Sessions, Scenarios)
- Storybook config with dark/light theme toggle and a11y addon

client/tsconfig.json

@@ -11,7 +11,8 @@
     "moduleDetection": "force",
     "noEmit": true,
     "jsx": "react-jsx",
-    "strict": true
+    "strict": true,
+    "types": ["vite/client"]
   },
-  "include": ["src"]
+  "include": ["src", ".storybook"]
 }