The server-host TextField on the connect form accepts a hostname or
hostname:port pair (e.g. kr.teamspeak.app:9987). Two improvements:
1. keyboardType: TextInputType.url surfaces '.', '/', ':' on the
primary on-screen keyboard plane so the user does not have to
switch to the symbols pane mid-address. Matches iOS Safari's
URL bar.
2. textCapitalization.none + autocorrect/enableSuggestions=false
prevents iOS from auto-capitalising the first letter or
'correcting' 'kr.teamspeak.app' to something else.
3. inputFormatters belt-and-braces:
* deny whitespace (handles tab-indented paste)
* lowercase pipeline (handles uppercase paste)
4. Visual affordances: prefix dns icon + 'host[:port]' hint.
Nickname field intentionally unchanged \u2014 may contain unicode,
mixed case, spaces.
flutter build ios --release --no-codesign: 30.7 s, Runner.app
30.0 MB. flutter analyze clean (6 pre-existing deprecation
warnings on Radio.groupValue/onChanged).