feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/node_modules/tailwindcss/lib/util/configurePlugins.js

@@ -0,0 +1,23 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+Object.defineProperty(exports, "default", {
+    enumerable: true,
+    get: function() {
+        return _default;
+    }
+});
+function _default(pluginConfig, plugins) {
+    if (pluginConfig === undefined) {
+        return plugins;
+    }
+    const pluginNames = Array.isArray(pluginConfig) ? pluginConfig : [
+        ...new Set(plugins.filter((pluginName)=>{
+            return pluginConfig !== false && pluginConfig[pluginName] !== false;
+        }).concat(Object.keys(pluginConfig).filter((pluginName)=>{
+            return pluginConfig[pluginName] !== false;
+        })))
+    ];
+    return pluginNames;
+}