Replace mock data in useVesting and useAirdrop with real on-chain queries

[whiteghost0001]

Problem

Both hooks/useVesting.ts and hooks/useAirdrop.ts return hardcoded mock data instead of querying the Soroban contracts:

// useVesting.ts
const mockSchedules: VestingSchedule[] = [ /* hardcoded */ ];
setTimeout(() => { setSchedules(mockSchedules); }, 800);

// useAirdrop.ts  
const mockCampaigns: AirdropCampaign[] = [ /* hardcoded */ ];
setTimeout(() => { setCampaigns(mockCampaigns); }, 800);

Additionally, claimVested() and distributeCampaign() simulate work with setTimeout rather than submitting real transactions via ContractService.

Expected Fix

• Replace the mock useEffect bodies with actual ContractService / Soroban RPC calls to fetch schedules and campaigns owned by the connected publicKey.
• Wire claimVested(scheduleId) and distributeCampaign(campaignId) through ContractService, sign via Freighter, and submit the XDR to the network.
• Handle loading and error states from real async responses.

Notes

• Depends on Replace placeholder contract IDs with env-var backed real addresses #1 (contract IDs must be set before this can be tested end-to-end).
• The ContractService class in lib/contracts.ts is already wired for deployToken, deployVesting, and deployAirdrop — the pattern can be followed for read calls.