Add negative test case for create-rsbuild pattern and fix overly permissive regex

[Copilot]

The regex pattern for detecting create-rsbuild commands was too permissive, matching creatersbuild (no separator) when it should only match create-rsbuild or create rsbuild.

Changes

• Added negative test case to verify npx creatersbuild is NOT matched
• Fixed regex pattern in getCliIntegrationFromAncestry() by making separator required:

  // Before: optional separator [\s\-]? allowed matching "creatersbuild"
  /(?:^|\s)create[\s\-]?rsbuild/i
  
  // After: required separator [\s\-] correctly rejects "creatersbuild"
  /(?:^|\s)create[\s\-]rsbuild/i

Pattern now correctly matches:

• ✅ create-rsbuild (dash)
• ✅ create rsbuild (space)
• ❌ creatersbuild (no separator)

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[Copilot]

Pull request overview

This PR fixes a regex pattern bug in the CLI integration detection logic. The previous regex was too permissive and would incorrectly match creatersbuild (without a separator) when it should only match create-rsbuild or create rsbuild.

Changes:

• Fixed regex pattern by making the separator character class [\s\-] required instead of optional (removed ?)
• Added a negative test case to verify npx creatersbuild is correctly rejected

Reviewed changes

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

File	Description
code/lib/create-storybook/src/services/VersionService.ts	Fixed regex pattern from `/(?:^
code/lib/create-storybook/src/services/VersionService.test.ts	Added negative test case to verify creatersbuild without separator is not matched