[NopeCharon]

Summary

• add a Default recipient email field to the Share By Email configuration page, stored in the share_by_email_default_recipient user attribute
• prefill the To field of the sharing form with it; the field remains editable and an empty setting keeps the current behaviour
• validate the address with PHPMailer in the same way FreshRSS core validates user email addresses (userController::validateEmailAddress()); an invalid address is rejected with the core user.email.feedback.invalid message and the previous value is kept
• add translations for all supported languages (de, en, fr, tr), document the option in the README and bump the version to 0.5.0

Fixes #129

Validation

End-to-end on a local FreshRSS edge instance (PHP 8.2 built-in server, SQLite) with the extension enabled:

• initial state: empty field on both the configuration page and the sharing form
• saving bob@example.net: stored, shown on the configuration page and prefilled in the sharing form
• saving not-an-email: redirected back to the configuration page with an error, previous value kept
• saving o'brien&co@example.net: stored as-is and correctly HTML-escaped in both forms
• saving carol@example.net : trimmed
• saving an empty value: the sharing form is no longer prefilled
• no PHP warnings or errors in the server output or FreshRSS logs

Static checks: composer run-script php-lint, composer run-script phtml-lint, phpcs, phpstan (with ../FreshRSS), and markdownlint-cli2 on the README.

[Alkarex]

Thanks!