feat(scp): add compact transfer output filter

[officialasishkumar]

Summary

• Add a native rtk scp wrapper that filters combined transfer output.
• Strip intermediate progress updates while preserving final byte summaries, warnings, and errors.
• Register scp for hook/discover rewrites and document command coverage.

Closes #1257

Test plan

• cargo fmt --all --check
• cargo test scp
• cargo clippy --all-targets && cargo test
• Manual testing: fake scp binary on PATH, rtk scp file.txt deploy@host:/tmp/file.txt output inspected

Important: All PRs must target the develop branch (not master).
See CONTRIBUTING.md for details.

[CLAassistant]

All committers have signed the CLA.

[pszymkowiak]

[w] wshm · Automated triage by AI

📊 Automated PR Analysis

✨ Type	feature
🟢 Risk	low

Summary

Adds a new rtk scp command that wraps the native scp binary, filtering out intermediate transfer progress updates while preserving final byte summaries, warnings, and error lines. The command is registered in the discovery/rewrite system and documented in the coverage guide.

Review Checklist

• Tests present
• Breaking change
• Docs updated

Linked issues: #1257

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Analyzed automatically by wshm · This is an automated analysis, not a human review.