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/.storybook/main.ts

@@ -0,0 +1,26 @@
+import type { StorybookConfig } from '@storybook/react-vite';
+
+import { dirname } from "path"
+
+import { fileURLToPath } from "url"
+
+/**
+* This function is used to resolve the absolute path of a package.
+* It is needed in projects that use Yarn PnP or are set up within a monorepo.
+*/
+function getAbsolutePath(value: string) {
+  return dirname(fileURLToPath(import.meta.resolve(`${value}/package.json`)))
+}
+const config: StorybookConfig = {
+  "stories": [
+    "../src/**/*.mdx",
+    "../src/**/*.stories.@(js|jsx|mjs|ts|tsx)"
+  ],
+  "addons": [
+    getAbsolutePath('@storybook/addon-vitest'),
+    getAbsolutePath('@storybook/addon-a11y'),
+    getAbsolutePath('@storybook/addon-docs')
+  ],
+  "framework": getAbsolutePath('@storybook/react-vite')
+};
+export default config;