Add routines module and full goal management

Routines: workout, meditation and must-do routines with timed, rep and
tick steps, sets and rest. A library screen, a builder with templates
and drag-to-reorder steps, and a full-screen player that auto-advances
timed phases, counts backgrounding and logs broken chains as partial.

Goals: a goal editor (deadline, colour, category, default class, archive),
routines linked to goals, and a goal field on tasks and routines. Tasks
added from inside a goal are now actually attached to it via parentId.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhQh614DMeYoQEH9SoMRUw

frontend/lib/Grounded/about/external/initial/CommitmentRequest.dart

@@ -2,6 +2,9 @@
 class CommitmentRequest {
   String? id;
 
+  /// The goal this task belongs to; null for a loose task.
+  String? parentId;
+
   String type;
 
   String commitmentClass;
@@ -26,6 +29,7 @@ class CommitmentRequest {
 
   CommitmentRequest({
     this.id,
+    this.parentId,
     this.type = "TASK",
     this.commitmentClass = "Standard",
     this.title = "",
@@ -42,6 +46,7 @@ class CommitmentRequest {
   Map<String, dynamic> toJson() {
     final Map<String, dynamic> data = <String, dynamic>{};
     data['id'] = id;
+    data['parentId'] = parentId;
     data['type'] = type;
     data['commitmentClass'] = commitmentClass;
     data['title'] = title;