fix(dashboard): remove simulated deposits, withdrawals, and transaction history

[privexlabs]

Summary

Authenticated financial dashboard widgets displayed fabricated transaction history and marked deposits/withdrawals as complete after client-side timers, with no ledger or provider backing.

Changes

• components/dashboard/funds-management.tsx: removed the hard-coded mockTransactions seed and the setTimeout-based fake success transitions. Transaction history is now loaded from /api/wallet/summary. Deposits are routed through the real /api/payments/initialize Paystack checkout flow. Withdrawals now report an honest "unavailable" state instead of fabricating a completed/pending transaction, since no payout provider is wired up yet.
• components/dashboard/loan/withdrawal-system.tsx: removed the hard-coded mockTransactions seed. Transaction history is now loaded from /api/transactions/ledger. The withdrawal handler no longer simulates a successful/pending transition via a timer; it now reports the same honest "unavailable" state.

Issues

Resolves #195

Verification

• Manual code review of the complete diff was performed; no unrelated files, snapshots, or generated files were touched.
• cargo build was not run.
• cargo test was not run.