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/asynckit/stream.js

@@ -0,0 +1,21 @@
+var inherits              = require('util').inherits
+  , Readable              = require('stream').Readable
+  , ReadableAsyncKit      = require('./lib/readable_asynckit.js')
+  , ReadableParallel      = require('./lib/readable_parallel.js')
+  , ReadableSerial        = require('./lib/readable_serial.js')
+  , ReadableSerialOrdered = require('./lib/readable_serial_ordered.js')
+  ;
+
+// API
+module.exports =
+{
+  parallel      : ReadableParallel,
+  serial        : ReadableSerial,
+  serialOrdered : ReadableSerialOrdered, 
+};
+
+inherits(ReadableAsyncKit, Readable);
+
+inherits(ReadableParallel, ReadableAsyncKit);
+inherits(ReadableSerial, ReadableAsyncKit);
+inherits(ReadableSerialOrdered, ReadableAsyncKit);