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/@testing-library/dom/dist/wait-for-element-to-be-removed.js

@@ -0,0 +1,52 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.waitForElementToBeRemoved = waitForElementToBeRemoved;
+var _waitFor = require("./wait-for");
+const isRemoved = result => !result || Array.isArray(result) && !result.length;
+
+// Check if the element is not present.
+// As the name implies, waitForElementToBeRemoved should check `present` --> `removed`
+function initialCheck(elements) {
+  if (isRemoved(elements)) {
+    throw new Error('The element(s) given to waitForElementToBeRemoved are already removed. waitForElementToBeRemoved requires that the element(s) exist(s) before waiting for removal.');
+  }
+}
+async function waitForElementToBeRemoved(callback, options) {
+  // created here so we get a nice stacktrace
+  const timeoutError = new Error('Timed out in waitForElementToBeRemoved.');
+  if (typeof callback !== 'function') {
+    initialCheck(callback);
+    const elements = Array.isArray(callback) ? callback : [callback];
+    const getRemainingElements = elements.map(element => {
+      let parent = element.parentElement;
+      if (parent === null) return () => null;
+      while (parent.parentElement) parent = parent.parentElement;
+      return () => parent.contains(element) ? element : null;
+    });
+    callback = () => getRemainingElements.map(c => c()).filter(Boolean);
+  }
+  initialCheck(callback());
+  return (0, _waitFor.waitFor)(() => {
+    let result;
+    try {
+      result = callback();
+    } catch (error) {
+      if (error.name === 'TestingLibraryElementError') {
+        return undefined;
+      }
+      throw error;
+    }
+    if (!isRemoved(result)) {
+      throw timeoutError;
+    }
+    return undefined;
+  }, options);
+}
+
+/*
+eslint
+  require-await: "off"
+*/