ui(connections): migrate connection forms to QueryaDialogCard

[ZhuchkaTriplesix]

Problem

Follow-up to #518 out-of-scope. Connection create/edit dialogs still use raw Container + BoxDecoration(color: popover) + ClipRRect, while Preferences, Extension Manager, New Connection type picker, URL dialog, etc. already use QueryaDialogCard (Material ink host + ambient text/icon re-apply).

Scope

Migrate shells for:

• postgresql_connection_form.dart
• mysql_connection_form.dart
• mongodb_connection_form.dart
• redis_connection_form.dart
• sqlite_connection_form.dart
• extension_connection_form.dart

Keep existing constraints / borderColor: muted / layout. Preserve QueryaDialogCard ambient DefaultTextStyle / IconTheme fix from #514/#516.

Out of scope

• SDUI text/password → shadcn TextField (separate; Form validation differs)
• Secrets only in driverOptions keys

Acceptance

• All six connection forms render via QueryaDialogCard
• No Material textTheme bloat / overflow regressions in dense chrome
• Create + edit flows still open/save/cancel
• Existing connection form widget tests stay green