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/loupe/lib/object.js

@@ -0,0 +1,31 @@
+import { inspectProperty, inspectList } from './helpers'
+
+export default function inspectObject(object, options) {
+  const properties = Object.getOwnPropertyNames(object)
+  const symbols = Object.getOwnPropertySymbols ? Object.getOwnPropertySymbols(object) : []
+  if (properties.length === 0 && symbols.length === 0) {
+    return '{}'
+  }
+  options.truncate -= 4
+  options.seen = options.seen || []
+  if (options.seen.indexOf(object) >= 0) {
+    return '[Circular]'
+  }
+  options.seen.push(object)
+  const propertyContents = inspectList(
+    properties.map(key => [key, object[key]]),
+    options,
+    inspectProperty
+  )
+  const symbolContents = inspectList(
+    symbols.map(key => [key, object[key]]),
+    options,
+    inspectProperty
+  )
+  options.seen.pop()
+  let sep = ''
+  if (propertyContents && symbolContents) {
+    sep = ', '
+  }
+  return `{ ${propertyContents}${sep}${symbolContents} }`
+}