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-interpolate/src/hcl.js

@@ -0,0 +1,21 @@
+import {hcl as colorHcl} from "d3-color";
+import color, {hue} from "./color.js";
+
+function hcl(hue) {
+  return function(start, end) {
+    var h = hue((start = colorHcl(start)).h, (end = colorHcl(end)).h),
+        c = color(start.c, end.c),
+        l = color(start.l, end.l),
+        opacity = color(start.opacity, end.opacity);
+    return function(t) {
+      start.h = h(t);
+      start.c = c(t);
+      start.l = l(t);
+      start.opacity = opacity(t);
+      return start + "";
+    };
+  }
+}
+
+export default hcl(hue);
+export var hclLong = hcl(color);