feat: add transaction feedback toast component with simulation and document

[vvm1004]

This pull request introduces a new reusable toast component for displaying real-time transaction status feedback in the UI. The main addition is the TxnFeedbackToast component, which provides visual notifications for each step of a transaction, including loading, success, and error states. The component is documented and registered for use in the design system, and supporting types have been added for type safety and extensibility.

New Transaction Feedback Toast Component

• Added the TxnFeedbackToast component in components/ui/murphy/Txn-Feedback/txn-feedback-toast.tsx, which displays transaction status updates (preparing, signing, sending, confirming, success, error) with appropriate icons, colors, and actions like retry or copy signature.
• Created a preview/demo page (components/txn-feedback-toast-preview.tsx) to showcase the toast and its various states, including controls for simulating transaction flows.
• Defined new TypeScript interfaces for transaction status and toast props in types/transaction/index.tsx to ensure strong typing and future extensibility.

Documentation and Registry Integration

• Added a comprehensive documentation page (content/docs/onchainkit/Txn-Feedback/txn-feedback-toast.mdx) with usage examples, installation instructions, and prop tables for the new toast component.
• Registered the toast component in the design system registry (public/r/txn-feedback-toast.json, registry/components/txn-feedback-toast.json, and registry.json) for discoverability and installation. [1] [2] [3]
• Updated exports in components/ui/murphy/index.tsx to include the new toast component, making it available for import throughout the project. [1] [2]

Meta and Navigation Updates

• Added "Txn-Feedback" to the docs meta navigation for easier access to the new documentation section.