feat(todo): the four tabs in Todo's frame, washed in strawberry, Settings from Browse

ADR 0033, step 1: go_router with a StatefulShellRoute and halkyon_ui's
NavigationFrame as Train's (D1), the tabs Today, Upcoming, Inbox and
Browse, each saying tasks come later (D2), every screen washing down in
strawberry (D3), and Settings over the tabs from Browse's cog, grouped in
cards: the operator's, the account, What's new and About Halkyon Todo,
the version below (D4). The account sheet and the empty home go.

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

@@ -16,6 +16,9 @@ dependencies:
   flutter:
     sdk: flutter
   flutter_bloc: ^9.1.1
+  # The tabs, each with its own stack of screens, and Settings over them
+  # (ADR 0033, D1), as Learn's and Train's.
+  go_router: ^18.0.2
   # What every Halkyon app is built around (a shared package): the instances a
   # device keeps accounts on, signing in through halkyon_base, each person's
   # dependencies opened and closed, with texts of its own.
@@ -36,6 +39,8 @@ dependencies:
   intl: ^0.20.3
   lucide_icons_flutter: ^3.1.20
   material_ui: ^1.5.0
+  # This build's version and number, for Settings' foot and what's new.
+  package_info_plus: ^10.2.2
   path: ^1.9.1
   path_provider: ^2.1.6
   serverpod_auth_idp_flutter: 4.0.4