Replace pkg/errors with fmt.Errorf

[fanyang89]

Motivation

• Standardize error wrapping to use the Go standard library instead of the deprecated github.com/pkg/errors usage across the codebase.
• Reduce external dependency surface by removing pkg/errors from module requirements.

Description

• Replaced errors.Wrap(err, "...") with fmt.Errorf("...: %w", err) across command handlers and parsers in cmd_mem.go, cmd_net.go, cmd_proc.go, cmd_syscall.go, cmd_vfs.go, cmd_vfs_raw.go, and parser.go.
• Replaced errors.Errorf uses with fmt.Errorf where present.
• Removed github.com/pkg/errors from go.mod and removed its entries from go.sum.
• Adjusted imports to rely on the standard fmt and errors packages where appropriate and ran gofmt to format changes.

Testing

• No automated tests were executed for this change.

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Codex Task

[fanyang89]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Nice work!

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