Forms and input

Text input is where most disposal leaks, un-localized strings, and jank enter a Flutter app. A form is a small state machine: fields hold text, a FormState validates them, and a ViewModel owns anything that touches the network or the clock. Keep those three responsibilities separate.

Read the reference for the task at hand:

• references/validation-sync-and-async.md — sync validator returning localized String?, AutovalidateMode choice, and the debounced-async-in-a-Notifier pattern (why async must NOT live in the sync validator).
• references/focus-and-keyboard.md — FocusNode lifecycle, traversal order, autofocus, FocusTraversalGroup, TextInputAction, onFieldSubmitted/onEditingComplete, keyboardType, autofillHints, TextInputFormatter, keyboard-avoidance.

Run scripts/check_forms.sh before a PR.

Non-negotiable rules