Add skeleton loading states for all data-fetching components

[Kingsman-99]

Overview

Data-fetching components show nothing or a spinner while loading. Replace spinners with skeleton screens that match the shape of the loaded content for a polished perceived-performance experience.

Acceptance Criteria

• Skeleton components for: invoice card, invoice detail page, leaderboard row, payment history row, creator profile, dashboard header stats
• Skeletons match the exact layout and proportions of the loaded content (same height, same column widths)
• Skeleton animation: shimmer effect using Tailwind animate-pulse or a custom CSS keyframe
• Skeletons shown during initial load AND during refetch (React Query isFetching)
• SkeletonInvoiceCard accepts a count prop to render N placeholders in a grid
• Skeletons work in both light and dark mode
• aria-busy="true" and aria-label="Loading..." on skeleton containers for screen readers
• No skeleton shown if data loads in under 200 ms (avoids flash for fast connections) — use a 200 ms delay before showing skeleton

[Turawa2]

@Turawa2 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I can work on the issue perfectly.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Turawa2 to this issue.

[Truphile]

@Truphile has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Kindly assign me to this task I can deliver a PR asap following the requirements and maintain the right architectural design needed... Thanks!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Truphile to this issue.

[lonerthefirst3-sudo]

@lonerthefirst3-sudo has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

i would love to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @lonerthefirst3-sudo to this issue.

[drips-wave]

Congratulations, @lonerthefirst3-sudo! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @lonerthefirst3-sudo: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[grantfox-oss]

🦊 GrantFox — @lonerthefirst3-sudo has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #368)
2. Your PR will be reviewed by the Stellar-split maintainers

Good luck! Track your progress on GrantFox.