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/lodash/_charsEndIndex.js

@@ -0,0 +1,19 @@
+var baseIndexOf = require('./_baseIndexOf');
+
+/**
+ * Used by `_.trim` and `_.trimEnd` to get the index of the last string symbol
+ * that is not found in the character symbols.
+ *
+ * @private
+ * @param {Array} strSymbols The string symbols to inspect.
+ * @param {Array} chrSymbols The character symbols to find.
+ * @returns {number} Returns the index of the last unmatched string symbol.
+ */
+function charsEndIndex(strSymbols, chrSymbols) {
+  var index = strSymbols.length;
+
+  while (index-- && baseIndexOf(chrSymbols, strSymbols[index], 0) > -1) {}
+  return index;
+}
+
+module.exports = charsEndIndex;