Small GUI enhancements

[ap0int3d]

Hi,
I open this topic to list some of the tiny visuals that I feel could be improved.

Making the suggested changes do not make WebSSH more useable but hopefully better looking.
There is no need to work on these urgently.

Login page:

If that makes a difference, my personal preference goes to the spacing currently used by the directory login. I prefer things being closer together and hence I would remove the green and red tips.

[ap0int3d]

2FA login page:

A "back" button could be useful in the 2FA page to go back to the starting login page if for some reason the user wants to change their login method.

[bifrost0x]

Thx a lot for your important help and support here :)

Update: the login and 2FA refinements requested here are now implemented on main via #158:

• the local/directory sign-in form uses the more compact spacing and no longer shows the green/red live validation tips
• the 2FA screen now provides a CSRF-protected Back to sign in action that cancels only the current browser-bound pending authentication

Further UI follow-up is included in #159:

• the Paper Ops contrast issue across login, registration, MFA, and password-change screens is fixed with regression coverage
• the File Manager no longer exposes redundant Move… toolbar actions or same-source directional Move buttons
• the destination folder is highlighted while dragging; self-drops, missing capabilities, conflicts, and unconfirmed server responses remain guarded
• cross-pane drag-and-drop and server-to-server transfers continue to use the existing transfer paths

The File Manager change is covered by JavaScript, template/i18n, and browser E2E tests in commit ddcd106.

Please feel free to retest the #158 changes on the current main build. The Paper Ops and File Manager follow-ups can be retested after #159 is merged.

PRs: #158, #159