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-time-format/locale/nl-NL.json

@@ -0,0 +1,10 @@
+{
+  "dateTime": "%a %e %B %Y %X",
+  "date": "%d-%m-%Y",
+  "time": "%H:%M:%S",
+  "periods": ["AM", "PM"],
+  "days": ["zondag", "maandag", "dinsdag", "woensdag", "donderdag", "vrijdag", "zaterdag"],
+  "shortDays": ["zo", "ma", "di", "wo", "do", "vr", "za"],
+  "months": ["januari", "februari", "maart", "april", "mei", "juni", "juli", "augustus", "september", "oktober", "november", "december"],
+  "shortMonths": ["jan", "feb", "mrt", "apr", "mei", "jun", "jul", "aug", "sep", "okt", "nov", "dec"]
+}