fix: add virtual: to virtual module source map ignore

[antfu]

Description

• add virtual: to the virtual module sourcemap ignore
• make \0 match for any position of the path, as it can't be a real path.

Additional context

unocss/unocss#2113 (comment)

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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