feat(fee): transfer tokens in fee deposit and withdraw (#1187)

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Closes #1187

Summary

Updates FeeContract so fee accounting is backed 1:1 by real token transfers:

1. Stores DataKey::Token during init(env, admin, token) and exposes it via get_token(env).
2. Pulls amount from caller to the contract via token::Client::new(&env, &token_addr).transfer(&caller, &contract_addr, &amount) during deposit.
3. Pushes amount from the contract to recipient via token::Client::transfer during withdraw after verifying both accumulated >= amount and on-ledger token balance.

Acceptance Criteria Mapping

• Deposit increases contract token balance and counter equally: Verified in test_deposit_and_withdraw and test_deposit_without_token_balance_fails_and_keeps_counter_in_sync.
• Withdraw decreases both equally: Verified in test_deposit_and_withdraw and test_withdraw_to_valid_recipient_succeeds.
• Counter can never exceed token balance in tests: Asserted across deposit/withdraw unit tests (client.get_accumulated() <= token_client.balance(&contract_id)).
• Token address exposed via a getter: Implemented FeeContract::get_token(env: Env) -> Result<Address, ContractError> with TTL extension and auth snapshot coverage.

Validation

• cargo test -p callora-fee

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Payout Wallet (Base Mainnet USDC / EVM): 0x3806cd592a508d1992Ed007C2F53de251C2E7452