docs: standardize loading and error state guidelines for page components

[Bilalishaq7]

Summary

Closes #532. This PR introduces architecture documentation clarifying how contributors must resolve UI loading and failure states within newly written page layouts to prevent fractured presentation experiences.

Changes

• Updates docs/state-management.md with detailed criteria on asynchronous lifecycle state flows.
• Adds explicit usage guides determining when to leverage structural page skeletons (CreatorSkeleton, CreatorCardSkeleton).
• Clarifies design guidelines separating application Error Boundaries from inline retry layouts.
• Introduces an idiomatic code architecture sample incorporating React Query hooks.

Testing

• pnpm lint
• pnpm build

Checklist

• Linked issue or backlog item
• Scope is limited to the stated change
• Updated docs if behavior or setup changed
• Added screenshots for UI changes when relevant