Fix: Remove trailing slashes from external URLs to prevent 404 errors

[hxrshxz]

Fixes #878

Description

Wikipedia and other external links were breaking with 404 errors due to Astro's trailingSlash: "always" config which was appending slashes to all URLs.

Changes

• Modified middleware to remove traling slashes from external URLs (except root domains like https://example.com/)
• Make sure that the middleware runs for all locales, including the default English local

Screencast.from.2025-10-11.23-03-24.mp4

[Copilot]

Pull Request Overview

Fixes external URL 404 errors caused by Astro's trailingSlash: "always" configuration by removing trailing slashes from external URLs while ensuring the middleware processes all locales including the default English locale.

• Refactored middleware to always process HTML links regardless of locale presence
• Added logic to strip trailing slashes from external URLs while preserving root domain paths
• Updated function signature to make currentLocale parameter optional

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[hxrshxz]

@ksen0 @davepagurek Please take a look