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/fi-FI.json

@@ -0,0 +1,10 @@
+{
+  "dateTime": "%A, %-d. %Bta %Y klo %X",
+  "date": "%-d.%-m.%Y",
+  "time": "%H:%M:%S",
+  "periods": ["a.m.", "p.m."],
+  "days": ["sunnuntai", "maanantai", "tiistai", "keskiviikko", "torstai", "perjantai", "lauantai"],
+  "shortDays": ["Su", "Ma", "Ti", "Ke", "To", "Pe", "La"],
+  "months": ["tammikuu", "helmikuu", "maaliskuu", "huhtikuu", "toukokuu", "kesäkuu", "heinäkuu", "elokuu", "syyskuu", "lokakuu", "marraskuu", "joulukuu"],
+  "shortMonths": ["Tammi", "Helmi", "Maalis", "Huhti", "Touko", "Kesä", "Heinä", "Elo", "Syys", "Loka", "Marras", "Joulu"]
+}