fix: only save updated settings to server, store theme and landingpage in localStorage as well

[ErikBjare]

Fixes https://github.com/ActivityWatch/aw-webui/issues/568

---

:rocket: This description was created by Ellipsis for commit fbe6019cbb61890d21690103ef0198dea1fbc71d

Summary:

This PR optimizes settings handling by removing unused code, refactoring state management, and ensuring crucial settings are stored locally for immediate access.

Key points:

• Removed unused code and refactored state handling in UserSatisfactionPoll.vue.
• Added JSON comparison function jsonEq in settings.ts to optimize settings storage.
• Implemented conditions to prevent unnecessary saving of default or unchanged settings in settings.ts.
• Ensured theme and landing page settings are stored in localStorage for immediate access.

---

Generated with :heart: by ellipsis.dev

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 10.52632% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 26.15%. Comparing base (bf16309) to head (fbe6019).

Files	Patch %	Lines
src/stores/settings.ts	10.52%	15 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #573 +/- ## ========================================== - Coverage 26.28% 26.15% -0.14% ========================================== Files 27 27 Lines 1613 1629 +16 Branches 276 285 +9 ========================================== + Hits 424 426 +2 - Misses 1132 1145 +13 - Partials 57 58 +1 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.