fix: identify uutils in cli output

[MukundaKatta]

Summary

• include (uutils) in sed --version / sed -V
• mention that sed is part of uutils in the help description
• add regression coverage for both CLI outputs

Fixes #407.

Tests

• cargo run --quiet -- --version
• cargo run --quiet -- --help
• cargo test uutils
• cargo test test_version
• cargo fmt --check
• git diff --check
• cargo test test_sed
• cargo test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.20%. Comparing base (f083fa0) to head (cd80e42).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #435   +/-   ##
=======================================
  Coverage   82.20%   82.20%           
=======================================
  Files          13       13           
  Lines        5542     5542           
  Branches      310      310           
=======================================
  Hits         4556     4556           
  Misses        983      983           
  Partials        3        3           

Flag	Coverage Δ
macos_latest	82.89% <100.00%> (ø)
ubuntu_latest	82.99% <100.00%> (ø)
windows_latest	0.00% <0.00%> (ø)

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[codspeed-hq]

Merging this PR will not alter performance

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 9 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	number_fix	517.8 ms	530.1 ms	-2.31%
⚡	access_log_subst	1.2 s	1.1 s	+5.77%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing MukundaKatta:codex/identify-uutils-in-cli (cd80e42) with main (f083fa0)}