feat: Adding sed command to rtk list

[Kaue-Romero]

Summary

• Add rtk sed as a system command that runs native sed unchanged and compacts large stdout.
• Preserve stderr, exit codes, and token tracking while shortening long sed output with head/tail retention.
• Document rtk sed in the command list and system command coverage docs.

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test
• Manual testing: rtk <command> output inspected

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

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[pszymkowiak]

[w] wshm · Automated triage by AI

📊 Automated PR Analysis

✨ Type	feature
🟢 Risk	low

Summary

Adds a new rtk sed system command that runs native sed unchanged and compacts large stdout by preserving head/tail lines and truncating long lines. Includes documentation updates across README, coverage docs, and system command docs, along with unit tests for the compaction logic and CLI argument pass-through.

Review Checklist

• Tests present
• Breaking change
• Docs updated

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

[Copilot]

Pull request overview

Adds a new rtk sed system command to the CLI, intended to run native sed while compacting large stdout and preserving tracking/exit-code behavior.

Changes:

• Added a Sed subcommand to the Clap CLI and wired it into run_cli() and is_operational_command().
• Introduced src/cmds/system/sed_cmd.rs to execute sed and compact stdout via head/tail retention + line truncation (with unit tests).
• Updated user-facing documentation to list rtk sed and its expected savings behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/main.rs	Registers rtk sed, dispatches execution, marks it operational, and adds an arg-parsing test.
src/cmds/system/sed_cmd.rs	Implements sed execution + stdout compaction and unit tests for the compaction behavior.
src/cmds/system/README.md	Documents the new system command module.
docs/guide/resources/what-rtk-covers.md	Adds sed to the coverage/savings table.
README.md	Adds rtk sed example usage to the command list.

[Copilot]

exec_capture forces stdin to Stdio::null(), so rtk sed will not work for common usages like echo foo | rtk sed 's/o/a/g' or rtk sed '...' (reading from stdin). Consider running sed via core::stream::run_streaming with StdinMode::Inherit (and ideally a streaming head/tail filter) so stdin is preserved and you don’t have to buffer unbounded stdout into memory for large outputs.

[Copilot]

This module-level doc comment says sed runs “while preserving native behavior”, but the implementation compacts/truncates stdout and (as written) disables stdin. Please reword to reflect what’s actually preserved (exit code, stderr) vs what changes (stdout compaction / potential stdin behavior).

Suggested change

	//! Runs sed and compacts large stdout while preserving native behavior.
	//! Runs sed, preserving the underlying exit code and stderr while compacting
	//! and truncating large stdout output.

[Copilot]

exec_capture(&mut cmd)? returns a fairly generic error; please add anyhow::Context here (similar to other command modules) so failures are attributable to sed execution (e.g., missing binary, spawn failure).