fix: correct returnsuccess redis status key

[Luzijano]

Summary

• Fix the returnsuccess Redis status set key from brdigeops:returnsuccess to bridgeops:returnsuccess.
• Add regression tests covering the bridge operation Redis namespace and the returnsuccess mapping.

Why

The misspelled Redis key can split returned-success operations into a different namespace than the other bridge operation status sets, making successful return tracking inconsistent.

Validation

• RED before fix: go test ./config failed on returnsuccess Redis key = "brdigeops:returnsuccess".
• GREEN after fix: go test ./config
• Regression suite: go test ./...

Bounty context

This is submitted as a small reliability/test-coverage improvement under the Bitgesell bounty/improvement program and aligns with #3.

AI assistance was used to inspect the issue, write the regression tests, and validate the fix.