feat(config): detect and warn unwrapped regex

[RahulGautamSingh]

Changes

managerFilePatterns (and other regex-or-glob options) accept both globs and regexes, where a regex must be wrapped in /.../. When a user writes a pattern that is clearly a regex but forgets the slashes, it is silently treated as a glob and never matches — with no feedback (see discussion #43741).

This adds a config validation warning when an unwrapped matcher contains regex-only tokens (a ^ start anchor, a $ end anchor, or a \d/\w/\s/\b character-class escape) that have no meaning in a glob, e.g.:

npm.managerFilePatterns: the pattern \.html?$ looks like a regex but is not wrapped in /.../, so it is treated as a glob. Wrap it in slashes if you intended a regex.

It's a warning (not an error) because the heuristic can't be certain, and legitimate globs should keep working.

Context

• This doesn't close an Issue, but I accept the risk that this PR may be closed if maintainers disagree with its opening or implementation

Addresses discussion #43741

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