server: Record ark protocol fees as counters + slogs.

Kobe Nysrequested to merge
fee-telemetry into master

Record ark protocol fees per op at success boundaries.

New `ark_protocol_fee_sat` counter and `ArkFeeRecorded` slog, labeled by `op_type` (board, offboard, refresh, lightning_send, lightning_receive).

Each op records once at its success edge; lightning_send records the net margin (quoted fee - CLN routing fee) with the gross components on the slog.

Migration adds `block_height` and `total_fee_sat` to `lightning_payment_attempt` for the success-side recording.

Edited by Kobe Nys

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