feat: implement user checkpoint dashboard and contract indexing

[pranavkonde]

This PR implements the User Checkpoint Dashboard, allowing users to view their complete history of checkpoints created on the Storacha platform. It includes necessary smart contract updates for efficient data indexing and a fully dynamic frontend dashboard.

Changes

Smart Contract (StorachaCheckpointer.sol)

• Added userCheckpoints mapping to track checkpoint IDs per user.
• Updated createCheckpoint to push new IDs into the user's history.
• Added getUserCheckpoints view function for efficient frontend retrieval.

Frontend Hooks & Logic (useStorachaCheckpointer.ts)

• Updated the hook to fetch the list of checkpoint IDs for the connected wallet.
• Updated the contract ABI in constants/index.ts to include the new getUserCheckpoints method.
• Added checkpointIds and refetchUserCheckpoints to the hook's return values.

UI Components & Dashboard (page.tsx)

• Created a new CheckpointList.tsx component to render individual checkpoint details (CID, Tag, Expiry, Status).
• Integrated the list into the main Dashboard page.
• Updated the "Stats Grid" to show real-time total checkpoint counts.
• Added a "Refresh" functionality to trigger manual data updates.

Verification Results

• The dashboard now correctly identifies the connected wallet and fetches associated checkpoints.
• Checkpoints are displayed with their real-time verification status (Pending/Verified) and expiration alerts.
• Empty states are handled gracefully with a call-to-action for new users.

Closes #28

[Fatumayattani]

Thank you @pranavkonde
This is thoughtful work and a really promising direction. The dashboard and indexing ideas fit well with where we want to take the project long term. For now, we’re keeping this phase focused on core protocol correctness and multichain flow, but I really appreciate the care you put into this and we’ll revisit it post-MVP.