Fix Snyk failure by removing carbon dependency

[cursor]

Removes the newly added github.com/dromara/carbon/v2 dependency and replaces its duration formatting usage with a small local formatter based on the Go standard library.

Verification:

• go test ./pkg/unpackerr

  

[davidnewhall]

What was the Snyk error?

[cursor]

CI failure diagnosed and fixed.

• Failure: golangci-lint failed on linux and darwin with varnamelen at pkg/unpackerr/duration.go, reporting parameter name d was too short for its scope.
• Cause: formatDuration used the one-letter parameter d across the function body, which violates the repo's enabled varnamelen lint rule.
• Fix: Renamed the parameter to duration and updated the internal assignment so the name is descriptive and lint-compliant.
• Follow-up commit: 35372a6

Validation: GOTOOLCHAIN=go1.26.4 go run github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2 run passed with 0 issues.

  

_{Sent by Cursor Automation: CI Failure Auto-Fixer}