Add user preference in settings to hide diet plan if not used

[dhituval]

Proposed Changes

Related Issue(s)

Fixes #852
#852

Fixes #852

Summary

This PR implements the ability for users to hide the Nutrition section from the Dashboard.

Motivation

Issue #852 requests adding a user preference to hide the diet plan / nutrition widget, allowing a more streamlined dashboard for users who do not track nutrition through the app.

Changes

• Added hideNutrition to UserProvider, persisted via SharedPreferencesAsync
• Added _loadHideNutrition() and setHideNutrition() for preference loading and saving
• Updated DashboardScreen to conditionally render DashboardNutritionWidget
• Added a settings toggle in SettingsPage so users can enable/disable the Nutrition display
• Verified that setting persists through app restarts

Testing

• Toggled setting in SettingsPage and verified UI updated immediately
• Restarted the app to confirm persistence
• Tested behavior on iOS simulator (iPhone 15)

If applicable, please link to any related issues (Closes #123,
Closes wger-project/other-repo#123, See also #123, etc.)

Please check that the PR fulfills these requirements

• [ x] Tests for the changes have been added (for bug fixes / features)
• [ x] Set a 100 character limit in your editor/IDE to avoid white space diffs in the PR
  (run dart format .)
• [x ] Updated/added relevant documentation (doc comments with ///).
• [ x] Added relevant reviewers.

[rolandgeider]

Hi and thanks for the PR!

I would say that we should be a bit more flexible and allow the users to hide / show other widgets in the home screen (they might want to hide the routines, but not the diet plan). We could save in the prefs a map with the visibility state of the different widgets?