Feature Request: Add a reusable loading and progress indicator for onchain actions

### Describe the solution you'd like

### Overview
OnchainKit provides components and hooks for executing onchain actions, but developers currently need to build their own loading and progress UI for common states such as “waiting for signature” or “transaction pending”
Without a standardized loading or progress indicator, each application reimplements similar UI patterns, which leads to inconsistent user experiences. Developers are also unsure which onchain states should be surfaced to users and how those states should be represented visually.

### Proposed Solution
Introduce a reusable loading and progress indicator that reflects common onchain action states such as awaiting signature, pending submission, and confirmation. The solution should provide sensible defaults while allowing developers to fully customize the UI to match their application design.