chore(justfile): Add just dart for easier Flutter dev

Format & lint Dart code.
Gives quick feedback without running the app if the code is valid.

justfile

@@ -185,6 +185,8 @@ cargo-clippy:
 lint-flutter:
     cd mobile && flutter analyze --fatal-infos .
 
+alias flutter-lint := lint-flutter
+
 alias fmt := format
 format: dprint flutter-format
 
@@ -430,4 +432,6 @@ migrate-coordinator: docker
 # Re-run database migrations for both app and coordinator
 migrate: migrate-app migrate-coordinator
 
+dart: flutter-format lint-flutter
+
 # vim:expandtab:sw=4:ts=4