fix(l10n): add missing dash in not_available_web tooltip

[dream-creator]

{"body": "Checklist:\n\n- [x] I have read and followed the contribution guidelines.\n- [x] I have read and followed the how to open a pull request guide.\n- [x] My pull request targets the main branch of the repo.\n- [x] I have tested these changes locally on my machine.\n\nCloses #1827\n\n## Description of changes\n\nThe tooltip for courses that are not available on mobile read:\n\n> Not available use the web version\n\nwhich was missing a separator. It now reads:\n\n> Not available - use the web version\n\nmatching the existing Coming soon - use the web version phrasing mentioned in the issue.\n\nUpdated app_en.arb and the generated localization files (app_localizations.dart, app_localizations_en.dart). The es/pt arb files were intentionally left untouched since translations are managed through Crowdin."}

[dream-creator]

Apologies — I opened this before noticing @kp-krish's #1828 already addresses #1827 with the same change. Withdrawing this duplicate in favor of the earlier PR. Thanks!