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/react/dist/index.js

@@ -0,0 +1,53 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+var _actCompat = require("./act-compat");
+var _pure = require("./pure");
+Object.keys(_pure).forEach(function (key) {
+  if (key === "default" || key === "__esModule") return;
+  if (key in exports && exports[key] === _pure[key]) return;
+  Object.defineProperty(exports, key, {
+    enumerable: true,
+    get: function () {
+      return _pure[key];
+    }
+  });
+});
+var _process$env;
+// if we're running in a test runner that supports afterEach
+// or teardown then we'll automatically run cleanup afterEach test
+// this ensures that tests run in isolation from each other
+// if you don't like this then either import the `pure` module
+// or set the RTL_SKIP_AUTO_CLEANUP env variable to 'true'.
+if (typeof process === 'undefined' || !((_process$env = process.env) != null && _process$env.RTL_SKIP_AUTO_CLEANUP)) {
+  // ignore teardown() in code coverage because Jest does not support it
+  /* istanbul ignore else */
+  if (typeof afterEach === 'function') {
+    afterEach(() => {
+      (0, _pure.cleanup)();
+    });
+  } else if (typeof teardown === 'function') {
+    // Block is guarded by `typeof` check.
+    // eslint does not support `typeof` guards.
+    // eslint-disable-next-line no-undef
+    teardown(() => {
+      (0, _pure.cleanup)();
+    });
+  }
+
+  // No test setup with other test runners available
+  /* istanbul ignore else */
+  if (typeof beforeAll === 'function' && typeof afterAll === 'function') {
+    // This matches the behavior of React < 18.
+    let previousIsReactActEnvironment = (0, _actCompat.getIsReactActEnvironment)();
+    beforeAll(() => {
+      previousIsReactActEnvironment = (0, _actCompat.getIsReactActEnvironment)();
+      (0, _actCompat.setReactActEnvironment)(true);
+    });
+    afterAll(() => {
+      (0, _actCompat.setReactActEnvironment)(previousIsReactActEnvironment);
+    });
+  }
+}