set_eip1559_fees sets maxFeePerGas without base fee headroom, so transactions are rejected when the base fee rises #2765

Describe the bug
EthereumClient.set_eip1559_fees (and AsyncEthereumClient.async_set_eip1559_fees) set maxFeePerGas = base_fee + max_priority_fee, with no headroom over the estimated next-block base fee (safe_eth/eth/ethereum_client.py:1956). If the base fee rises before the transaction is mined, which it can by up to 12.5% per block, the node rejects it with max fee per gas less than block base fee.

This is what makes safe-cli fail to execute transactions (safe_tx.execute(..., eip1559_speed=TxSpeed.NORMAL) → web3.exceptions.Web3RPCError: 'max fee per gas less than block base fee'), as previously reported in safe-global/safe-cli#104 and safe-global/safe-cli#362; we hit it with safe-cli 1.9.0 on Sepolia.

To Reproduce
With anvil --port 8546 --base-fee 1000000000:

from eth_account import Account
from safe_eth.eth import EthereumClient
from safe_eth.eth.ethereum_client import TxSpeed

client = EthereumClient("http://127.0.0.1:8546")
w3 = client.w3
account = Account.from_key("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80")  # anvil test account
tx = client.set_eip1559_fees({"from": account.address, "to": Account.create().address, "value": 1,
                              "gas": 21000, "nonce": w3.eth.get_transaction_count(account.address)})
base, _ = client.estimate_fee_eip1559(TxSpeed.NORMAL)
w3.provider.make_request("anvil_setNextBlockBaseFeePerGas", [hex(base * 9 // 8 + 1)])  # one block's max rise
w3.eth.send_raw_transaction(account.sign_transaction(tx).raw_transaction)

Output on main (416a252):

estimated base fee 1000000000 wei -> maxFeePerGas 1000000000 (priority 0)
next block base fee rises one block's max to 1125000001 wei
{'code': -32003, 'message': 'max fee per gas less than block base fee'}

Expected behavior
maxFeePerGas leaves headroom for the base fee to rise, as web3.py does when it fills EIP-1559 fees (maxPriorityFeePerGas + 2 * baseFeePerGas, web3/_utils/transactions.py). Only the actual base fee is charged, so the headroom does not increase the cost.

Additional context
I have a fix (sync and async clients) with tests and will open a PR.