⚡ performance optimization: batch fetch availableDates

Removed the 100ms artificial delay in `loadMenuDataFromAPI` and switched from sequentially awaiting fetch requests to concurrently awaiting requests in batches of 5 using `Promise.all`. Preserved original chronological ordering of array elements.

Co-authored-by: TauNeutrino <1600410+TauNeutrino@users.noreply.github.com>

benchmark_loadMenuDataFromAPI.js

@@ -0,0 +1,22 @@
+const fs = require('fs');
+
+async function benchmark() {
+    // We will simulate the same exact loop in src/actions.js
+    let availableDates = Array.from({length: 30}).map((_, i) => ({ date: `2024-01-${i+1}`}));
+    const totalDates = availableDates.length;
+    let completed = 0;
+
+    console.log(`Starting benchmark for ${totalDates} items (Sequential with 100ms artificial delay)`);
+    const start = Date.now();
+    for (const dateObj of availableDates) {
+        // mock fetch
+        await new Promise(r => setTimeout(r, 50)); // simulate network delay
+
+        completed++;
+        await new Promise(r => setTimeout(r, 100)); // the artificial delay in codebase
+    }
+    const end = Date.now();
+    console.log(`Sequential loading took ${end - start}ms`);
+}
+
+benchmark();