fix: metadata image route Windows path escaping (#71615)
### Why?
When handling the `opengraph-image` size exceeding the limit, we mapped
with string literal between Rust and JavaScript. The Rust string literal
contains backslashes `\` on Windows, incompatible with JavaScript string
syntax.
Fixes #71582
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Co-authored-by: Donny/강동윤 <kdy1997.dev@gmail.com>
