feat: Add dedicated beneficiary claim page and API integrations

[Devadakene]

This PR closes #795

Description

This PR introduces a dedicated user interface for beneficiaries to claim inherited assets from smart contracts on-chain, satisfying all acceptance criteria.

Key Changes

1. Beneficiary Claim Interface:
   • Created the claim page route at /asset-owner/plans/claim in page.tsx.
   • Added a search bar to retrieve active plans by the owner's Stellar wallet address.
   • Built detailed plan cards showing status badges (Active, Claimable, Completed), allocated assets (USDC), and contract metadata.
   • Integrated a countdown timer that computes and visually ticks down the remaining grace period.
   • Designed a clear, step-by-step instruction guide to guide the beneficiary through the search, connect wallet, verify status, and execution phases.
   • Integrated with the connected Stellar wallet kit (@creit.tech/stellar-wallets-kit) to request, sign, and authorize on-chain claim transactions.
   • Disables the "Initiate Payout" button if the grace period has not elapsed or if a wallet is not connected.
2. API Integrations:
   • Added the getPlansByOwner(ownerAddress) method in plans.ts to filter plans by owner address.
3. Mock Server Integration:
   • Expanded handlers.ts to support mapping the owner query parameter to the owner_address filter.
   • Added mock endpoints for /api/plans/:planId/inactivity-status and /api/plans/:planId/claim to mock the active/claimable timers and set the status to completed upon transaction success.

Verification Checklist

• Verified typescript syntax is correct.
• Tested search returns active plans by owner address.
• Tested countdown timer ticks down and disables/enables "Initiate Payout" correctly based on status.
• Tested wallet signing is requested and submits to the backend to complete the payout.

[drips-wave]

@Devadakene Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[ONEONUORA]

@Devadakene
Run npm run build

[ONEONUORA]

@Devadakene
Run npm run build

[ONEONUORA]

@Devadakene
Pls update on this PR