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/is-callable/.editorconfig

@@ -0,0 +1,31 @@
+root = true
+
+[*]
+indent_style = tab
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+max_line_length = 150
+
+[CHANGELOG.md]
+indent_style = space
+indent_size = 2
+max_line_length = off
+
+[README.md]
+indent_style = off
+indent_size = off
+max_line_length = off
+
+[*.json]
+max_line_length = off
+
+[Makefile]
+max_line_length = off
+
+[coverage*/**/*]
+indent_style = off
+indent_size = off
+max_line_length = off