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/d3-array/src/greatest.js

@@ -0,0 +1,29 @@
+import ascending from "./ascending.js";
+
+export default function greatest(values, compare = ascending) {
+  let max;
+  let defined = false;
+  if (compare.length === 1) {
+    let maxValue;
+    for (const element of values) {
+      const value = compare(element);
+      if (defined
+          ? ascending(value, maxValue) > 0
+          : ascending(value, value) === 0) {
+        max = element;
+        maxValue = value;
+        defined = true;
+      }
+    }
+  } else {
+    for (const value of values) {
+      if (defined
+          ? compare(value, max) > 0
+          : compare(value, value) === 0) {
+        max = value;
+        defined = true;
+      }
+    }
+  }
+  return max;
+}