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/tailwindcss/lib/util/validateFormalSyntax.js

@@ -0,0 +1,26 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+Object.defineProperty(exports, "backgroundSize", {
+    enumerable: true,
+    get: function() {
+        return backgroundSize;
+    }
+});
+const _dataTypes = require("./dataTypes");
+const _splitAtTopLevelOnly = require("./splitAtTopLevelOnly");
+function backgroundSize(value) {
+    let keywordValues = [
+        "cover",
+        "contain"
+    ];
+    // the <length-percentage> type will probably be a css function
+    // so we have to use `splitAtTopLevelOnly`
+    return (0, _splitAtTopLevelOnly.splitAtTopLevelOnly)(value, ",").every((part)=>{
+        let sizes = (0, _splitAtTopLevelOnly.splitAtTopLevelOnly)(part, "_").filter(Boolean);
+        if (sizes.length === 1 && keywordValues.includes(sizes[0])) return true;
+        if (sizes.length !== 1 && sizes.length !== 2) return false;
+        return sizes.every((size)=>(0, _dataTypes.length)(size) || (0, _dataTypes.percentage)(size) || size === "auto");
+    });
+}