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/nanoid/.claude/settings.local.json

@@ -0,0 +1,14 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(node /workspaces/nanoid/test/check-versions.js)",
+      "Bash(echo \"Exit: $?\")",
+      "Bash(node --version)",
+      "Bash(node --experimental-strip-types test/check-prebuild.js)",
+      "Bash(node --experimental-strip-types test/update-prebuild.js)",
+      "Bash(node test/check-versions.js)",
+      "Bash(node bin/nanoid.js --version)",
+      "Bash(node bin/nanoid.js -s 10)"
+    ]
+  }
+}