fix: kebab-case CLI flags broke in peowly migration

[Copilot]

• Identify root cause: peowly doesn't auto-convert camelCase flag keys to kebab-case (unlike meow), so engineCheck → --engineCheck only, not --engine-check
• Rename all 7 multi-word flag keys to kebab-case in cli.js
• Update cli.flags destructuring to kebab-case rename syntax (also serves as a TypeScript compile-time check)
• Add CLI flag names test suite in test/integration.js with 7 regression tests covering every previously broken flag
• Add negative test (rejects an unknown flag) to prove assertFlagRecognised would catch a regression — verifies that --engineCheck (camelCase) is correctly rejected as unknown

Original prompt

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This section details on the original issue you should resolve

<issue_title>Investigate regressions</issue_title>
<issue_description>See eg. mochajs/mocha#5738 and bcomnes/domstack#214</issue_description>

<agent_instructions>research widely to find the root cause of this regression and make sure to patch it and any other similar regression</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Investigate regressions #124

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[Copilot]

Pull request overview

This PR fixes a critical regression introduced during the migration from meow to peowly. Unlike meow, peowly does not automatically convert camelCase flag object keys to kebab-case CLI flag names, causing all multi-word CLI flags to break for users.

Changes:

• Renamed 7 multi-word flag keys from camelCase to kebab-case in cli.js flag definitions
• Updated flag destructuring to use kebab-case rename syntax (provides TypeScript compile-time safety)
• Added comprehensive test suite with 7 regression tests and 1 negative test to prevent future regressions

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
cli.js	Renamed 7 flag keys to kebab-case ('engine-check', 'peer-check', 'version-check', 'ignore-dev', 'workspace-ignore', 'engine-ignore', 'engine-no-dev') and updated destructuring syntax
test/integration.js	Added assertFlagRecognised helper and 8 tests (7 positive + 1 negative) to verify all multi-word flags work correctly

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