Add invoice payment event replay for indexer recovery

[Kingsman-99]

Label: complexity: high
Points: 200

Description

If an off-chain indexer misses events (downtime, RPC issues), there's no on-chain way to "replay" historical state for a given invoice beyond manually re-fetching the audit log, which doesn't carry full payment amounts/structured data.

Technical Context

Involves lib.rs — replay_invoice_events(env, invoice_id), re-emitting invoice_created, each historical payment_received (from invoice.payments), and the current status event (invoice_released/invoice_refunded if applicable) in sequence, allowing an indexer to resync by calling this once and rebuilding state from the replayed event stream.

Acceptance Criteria

• Re-emits one payment_received-equivalent event per entry in invoice.payments, in original order
• Re-emits the terminal status event matching current invoice.status if not still Pending
• Replayed events are clearly tagged (e.g. a replay: true topic marker) so indexers can distinguish them from live events and avoid double-counting
• Pure read+emit — no state mutation, callable by anyone
• Test verifies the exact sequence and count of replayed events matches the invoice's actual payment history
• All existing cargo tests pass
• cargo clippy passes with zero warnings

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[1sraeliteX]

Hello, I would like to work on this issue