Summary

This pull request reverts a behavior change from #10535 --- previously, keychain support was disabled in the Windows portable application. After #10535, Electron safeStorage is used to encrypt secure settings in the Windows portable app before saving them in Joplin's database. This may break the portability of Joplin Portable.

Notes:

• After Desktop: Use Electron safeStorage for keychain support #10535 secure settings are still stored in Joplin's database (not the system keychain). Desktop: Use Electron safeStorage for keychain support #10535 encrypted these settings.
• To prevent data loss, this pull request preserves the ability to read safeStorage-encrypted settings in the portable app.
• An alternative to this pull request could be to add an "encrypt secure keys" setting only available to users of the portable app that controls whether safeStorage can be used.

Testing plan

This pull request includes automated tests that:

• Verify that settings not present in the database are loaded from the KeychainService, if available.
• Verify that passwords are saved to the database (without processing by KeychainService) when KeychainService is read-only.
• In the case where KeychainService is read-only, verifies that passwords saved using the default setting storage are preferred to those stored in the keychain.

Manual testing (in progress):

1. Build the Windows portable app.
2. Download v3.1.4 of the Windows portable app.
3. Start the just-downloaded version of Joplin.
4. Open the development tools. Run Setting.value('keychain.supported') and verify that the output is 1.
5. Enable the backup plugin and restart Joplin.
6. Set the backup password to testing and enable password-protected backups.
   • testing must be set in both the password and confirm inputs.
7. Save settings and quit Joplin.
8. Replace the downloaded JoplinPortable.exe with the built JoplinPortable.exe.
9. Start the built JoplinPortable.exe.
10. Verify that the backup password is still set to testing (in settings, using dev tools).
11. Change the backup password to test and save.
    • test must be set in both the password and confirm inputs.
12. Restart Joplin.
13. Verify that the backup password is still set to test.
14. Go to Help > About and verify that keychain support is listed as No.
15. Start a development build of Joplin (Windows 11).
16. Go to Help > About and verify that keychain support is listed as Yes.
17. Open the development console and run Setting.setValue('keychain.supported', -1).
18. Restart Joplin.
19. Go to Help > About and verify that keychain support is listed as Yes.
20. Verify that the development tools contain tried to set and get password. Result was: mytest.