Ramp transfers are marked `completed` without any on-chain settlement (both directions)

[resourcefulmind]

Area: API / ramps settlement

Ramp transfers reach status: completed while no on-chain transaction occurs and balances do not change, in both directions:

• On-ramp: a Lightspark on-ramp reached completed with signature: null; the destination wallet received 0 of the token.
• Off-ramp: a Lightspark off-ramp reached completed with signature: null; the source wallet's balance was unchanged, so the amount never left.

A plain on-chain transfer in the same environment settles correctly (a real signature, balances move), so this is specific to the ramp settlement path, not an environment limitation.

Reproduce

curl "$BASE/v1/payments/transfers/$TRANSFER_ID" -H "Authorization: Bearer $KEY"
#   status completed, signature null, slot null
curl "$BASE/v1/wallets?includeBalances=true" -H "Authorization: Bearer $KEY"
#   the affected wallet balance is unchanged

Impact: a reconciliation process or a caller polling for completed will believe funds moved when they did not. On money movement this is a correctness problem.
Suggested fix: do not mark a ramp transfer completed until the on-chain leg confirms with a real signature. Use an intermediate status such as settling for the fiat-settled-but-not-yet-delivered state.

[multipletwigs]

Some providers actually do settle onchain for devnet while some don't, will document this properly. But this issue should be related to how the transfer table is being shown on Payments which needs a fix.