[Medium] Add credential loading states

[Josie123-Dev]

Task Description

Implement loading states for credential operations:

• Show loading spinners
• Disable buttons during loading
• Show skeleton screens
• Handle loading errors
• Show loading progress

Requirements

• Loading indicators
• Button states
• Skeleton screens
• Error handling
• Progress bars

Acceptance Criteria

• Loading is shown
• Buttons are disabled
• Skeletons appear
• Errors are handled
• Progress is shown

[waterWang]

Implemented credential loading states in PR #156: LoadingSpinner, SkeletonCard, SkeletonAnalytics components; saving state in edit modal; initial loading skeleton in vault. 53/53 tests passing.

[rhemy-arc]

Hi, I’d like to take on this issue.

I’ll implement clear loading states for credential operations, including spinners, disabled button states, skeleton screens, error handling, and progress indicators. I’ll follow the existing UI patterns and make sure each acceptance criterion is covered with a clean and responsive implementation.

[grantfox-oss]

🦊 GrantFox — @rhemy-arc has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #70)
2. Your PR will be reviewed by the GuardZero144 maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@rhemy-arc's PR #176 was approved and merged by @Josie123-Dev.

🏆 @rhemy-arc: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (452 total points). Track your full progress on GrantFox.

👏 Great work, @rhemy-arc! Keep contributing to GuardZero144.