### Added
- M2 Material 3 Expressive UI — the app is fully navigable now: the
  provider/permission onboarding gate, the lists overview (smart lists + user
  lists grouped by account), and the task list (swipe-to-complete / -delete,
  inline add, smart-list section headers), detail, and create/edit screens, all
  wired to the M1 ViewModels.
- M3 detail/edit polish: a "Progress" slider (percent-complete, 5% detents,
  written to `Tasks.PERCENT_COMPLETE`) and conflict-safe saves — `updateTask`
  re-checks the provider's `last_modified` against the value captured when the
  form loaded and surfaces an overwrite-or-cancel prompt instead of clobbering an
  external change (e.g. a DAVx5 sync).
- M4 subtasks (UI): reparent — a full-width, searchable "Parent task" sheet on
  the edit form, with candidates grouped by due-date section, files a task under
  any active top-level task in its list (or "None" to promote it); switching list
  clears the now-invalid parent. Tapping a subtask in the detail screen opens its
  own detail, which shows a "Part of …" parent card. On the task list a parent has
  a dedicated expand button that reveals its children as a nested grouped run,
  ending with an inline "add a subtask" row (an opt-out toggle is planned for the
  M6 settings screen).
- Priority is coloured by level (green / amber / red pastels) on the list, detail,
  and edit screens.

### Fixed
- Overview open-counts now count top-level tasks only, so subtasks — and
  especially open subtasks under a completed parent — no longer inflate a list's
  "N open" or the smart-list counts.
- Swipe-to-delete now reveals its red background + icon as you drag (tracking the
  live direction, not just the settled target), and a floating "Deleted · Undo"
  chip defers the actual delete so it can be restored.