Implements Background Rollback Notary Proofs

[Step7750]

Ref CSF-1105

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Note

Medium Risk
Changes the rollback-trade handling path to optionally generate and submit notary proofs, adding new network calls and feature-flagged behavior with a legacy fallback. Risk is moderate due to new API dependencies and potential failure modes around proving/token fetching.

Overview
Rollback handling now supports background notary proofs. When rollback trades are detected, pingRollbackTrades can (if enabled via /v1/meta/notary and not Firefox) fetch a notary token, prove relevant trade history via NotaryProve, and submit the proof to /v1/trades/notary instead of sending the legacy rollback ping.

If background proving fails, the code reports the error to /v1/trades/:tradeId/report-error and falls back to the existing PingRollbackTrade flow. This also centralizes the trade-history fetch limit via MAX_TRADE_HISTORY_FETCH and wires new bridge handlers FETCH_NOTARY_META/FETCH_NOTARY_TOKEN into the request handler map.

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