fix: allow both http and https for server URL, default to https if mi…

[kiingxo]

Proposed Changes

• Allow both http and https protocols for the server URL.
• If the user does not specify a protocol, default to https://.
• Prevents connection issues for users with self-hosted HTTP servers or strict HTTPS-only servers.

Related Issue(s)

Closes #860

Please check that the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Set a 100 character limit in your editor/IDE to avoid white space diffs in the PR (run dart format .)
• Updated/added relevant documentation (doc comments with ///).
• Added relevant reviewers.

[rolandgeider]

hey @kiingxo thanks for the PR!

We would need to use the normalizeServerUrl helper to lib/widgets/auth/server_field.dart since currently the validation would not work