feat(app): a reset of the keys without the phrase, its banner, and the keys' proof key for a password that signs in (ADR 0020, D31–D35)

SimpleLogin's sheet, its password and its recovery phrase both lost:
under the lost-password step's phrase field, Lost your recovery phrase
too? says what stays and what is lost and asks for new keys
(`keys.startReset`) with the sign-in of a moment ago, which the device
then drops. The next sign-in says when while it waits, and once due
offers new keys, the sign-up's own password and phrase steps
(`keys.completeReset`), or the password, which calls it off (D31).

Every app's home shows `KeysResetBanner` where "too old" shows, and the
account section's SimpleLogin row the same words (`KeysResetNotice`),
each with Call it off, the password's proof alone
(`keys.callOffResets`, D32), and, once due on a device that holds the
keys, Finish here, which wraps the same keys anew (D33, D35). Both show
only a reset of an account that signs in with SimpleLogin alone; ADR
0017's resets show in its own section, which now shares `AlertBox` with
them.

An account whose password signs in has no Forgot your password? there,
and is asked its password and a code once while its keys lack the proof
key, at a sign-in or on adding SimpleLogin (`password.setProofKey`,
D34). `PasswordUnlock` carries the proof key, which its forgetting
leaves, and the keys' password proves for a purpose given.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_flutter/lib/src/home/home_screen.dart

@@ -1,3 +1,4 @@
+import 'package:halkyon_app/halkyon_app.dart';
 import 'package:halkyon_todo_flutter/l10n/app_localizations.dart';
 import 'package:halkyon_todo_flutter/src/account/account_sheet.dart';
 import 'package:halkyon_ui/halkyon_ui.dart';
@@ -5,7 +6,8 @@ import 'package:lucide_icons_flutter/lucide_icons.dart';
 import 'package:material_ui/material_ui.dart';
 
 /// A signed-in person's home: nothing yet, as Todo keeps nothing until its
-/// first model, and the way to the account.
+/// first model, and the way to the account; a reset of the person's keys
+/// waiting above it (`KeysResetBanner`).
 class const HomeScreen({super.key}) extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
@@ -21,12 +23,19 @@ class const HomeScreen({super.key}) extends StatelessWidget {
           ),
         ],
       ),
-      body: Center(
-        child: EmptyListMessage(
-          icon: LucideIcons.listChecks,
-          title: l10n.homeEmptyTitle,
-          hint: l10n.homeEmptyHint,
-        ),
+      body: Column(
+        children: [
+          const KeysResetBanner(),
+          Expanded(
+            child: Center(
+              child: EmptyListMessage(
+                icon: LucideIcons.listChecks,
+                title: l10n.homeEmptyTitle,
+                hint: l10n.homeEmptyHint,
+              ),
+            ),
+          ),
+        ],
       ),
     );
   }