feat(todo): the person's projects, sealed and synced, the Inbox made once (ADR 0033, D5, D6)

TodoPerson opens the person's own sync database in their folder,
halkyon_app's SyncService behind AppCompatibility, their key (TodoKeys,
Train's copied with Todo's own key IDs) and their projects, and closes
them in that order, the key last. A project is sealed for its row; a
readable, foreign or moved row shows locked, and a device without the
account's keys reads and writes nothing. The Inbox is the row under an
ID keyed by the account, so every device makes the same one and the
instance can't tell which it is; it can't be deleted. Settings shows
Sync's card first and the cog its dot while sync fails, as Learn's.

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/pubspec.yaml

@@ -13,6 +13,8 @@ environment:
 resolution: workspace
 
 dependencies:
+  clock: ^1.1.3
+  equatable: ^3.0.0
   flutter:
     sdk: flutter
   flutter_bloc: ^9.1.1
@@ -45,6 +47,7 @@ dependencies:
   path_provider: ^2.1.6
   serverpod_auth_idp_flutter: 4.0.4
   serverpod_flutter: 4.0.4
+  serverpod_offline_sync_client: 0.0.10
 
 dev_dependencies:
   flutter_driver: