fix: duplicate path error problem issue(#610)

[Arunanshu655]

Hey everyone! 👋
I was trying to set up the site locally on Windows and ran into a build error ( basically duplicate path error) that made it impossible to run.

What was happening

On LINUX/macOS, folders starting with a dot (like .well-known) are hidden at the OS level, so when Laika scans the src/ directory it skips .well-known entirely. Then the explicit .addDirectory("src/.well-known", ...) call in LaikaBuild.input adds it back at the correct virtual path — everything works as intended.
On Windows however, dot-folders are not hidden by default. So Laika's directory scan picks up src/.well-known from addDirectory("src"), and then the explicit addDirectory("src/.well-known", ...) tries to register the same path a second time — causing a duplicate path error that crashes the build before it even starts.

What I have done

I get a reference to the src/.well-known path, check if it exists, and if it does I set the dos:hidden attribute on it using java.nio.file.Files.setAttribute — so Windows treats it the same way Linux/macOS does natively. This uses standard Java NIO which is available on any JDK, so it should work consistently across all Windows machines. On Linux/macOS this block is skipped entirely, so existing workflows are completely unaffected.

I think this PR is relevant to the issue no. #610

@armanbilge if possible please review my PR