* 💡 **What:** Implemented a generic `debounce` utility and applied it to the `Navbar` component's window resize event listener (150ms delay). Added a `.cancel()` method to the debounce utility to prevent memory leaks/errors on unmount.
* 🎯 **Why:** The `resize` event fires rapidly, causing `getBoundingClientRect` (a layout-thrashing operation) to run excessively, impacting performance.
* 📊 **Measured Improvement:** In a benchmark test simulating 100 rapid resize events:
* **Baseline:** 200 calls to `getBoundingClientRect`.
* **Optimized:** 2 calls to `getBoundingClientRect`.
* **Result:** ~99% reduction in layout calculations during rapid resizing.
* Added `src/components/layout/Navbar.perf.test.tsx` to prevent regression.
