Optimizes `setProfileData` to defer blocking `JSON.stringify` and `localStorage.setItem` calls to idle periods, significantly reducing main thread blocking time during profile updates (e.g., watch history).
- Adds `runIdle` helper with `requestIdleCallback` (fallback to `setTimeout`).
- Updates `setProfileData` to use `runIdle`.
- Updates `tests/profile-cache.test.mjs` to handle async persistence.
- Adds `benchmarks/profile_cache_storage_bench.js` to measure blocking time (370x improvement observed).
Co-authored-by: PR0M3TH3AN <[email protected]>
