disable buttons in account.php

[simonLeary42]

• disabled key_paste, key_github submit buttons by default
• added self-closing tags to some elements
• added hook to enable/disable key_github
• modified file-upload hook from disable import button until file is uploaded, unmask invalid uploaded file error #324 to match style of the other 2 hooks

Screen.Recording.2025-09-30.at.1.48.24.PM.mov

[Copilot]

Pull Request Overview

This PR improves the user experience of the new SSH key modal by implementing proper button state management. The changes ensure that submit buttons are disabled by default and only enabled when users provide valid input.

• Added disabled attribute to submit buttons by default
• Implemented JavaScript handlers to enable buttons based on user input validation
• Updated HTML to use self-closing tags and removed unnecessary ID attributes

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