docs: add redirect config for CaseSensitivePlugin

[Timeless0911]

Summary

Add redirect config for CaseSensitivePlugin.

Related links

#12532

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull request overview

This PR adds a client-side redirect configuration to handle the URL change for the CaseSensitivePlugin documentation from its old path (warn-case-sensitive-modules-plugin) to its new path (case-sensitive-plugin).

Key Changes

• Imports pluginClientRedirects from @rspress/plugin-client-redirects package
• Configures a redirect from the old plugin documentation URL to the new URL
• Adds the redirect plugin to the rspress configuration

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[Copilot]

The redirect configuration only includes the English documentation path. Since this project has both English and Chinese documentation (as seen in the /zh locale), a redirect should also be added for the Chinese path to ensure users accessing the old Chinese URL are properly redirected.

Consider adding a redirect for: /zh/plugins/webpack/warn-case-sensitive-modules-plugin to /zh/plugins/webpack/case-sensitive-plugin

Suggested change

	},
	},
	{
	from: '/zh/plugins/webpack/warn-case-sensitive-modules-plugin',
	to: '/zh/plugins/webpack/case-sensitive-plugin',
	},