Replace the three ItemsControl sections (Overdue/Open/Completed) with a single
flat Rows collection (HeaderRow | TaskRowViewModel) bound to a ListBox +
VirtualizingStackPanel, so the realized container count stays bounded instead
of growing with the list (measured: ~7-8 realized containers at any scroll
position with 1000 source rows). Group headers become regular row entries,
each section is simply omitted from Rows when empty, and the Completed
section's Clear-completed action moves onto the header row itself.
SectionFor/ReorderAsync/FindNextInSameSection now read a row's section off
the nearest preceding HeaderRow in Rows instead of three separate bound
collections, and ScrollSelectedIntoView goes through ListBox.ScrollIntoView so
it still works for rows outside the realized window. Drag/reorder behavior,
grouping/counts, and the Clear-completed button are unchanged.
Auto-scroll-while-dragging and the cross-section reorder bug are explicitly
out of scope (follow-up tasks).
Slice 6 of the worker state and queue consolidation refactor.
* Drop Manual, Planning, Planned, Draft, Waiting from the TaskStatus enum
and from the EF value converter; only the lifecycle values remain
(Idle, Queued, Running, Done, Failed, Cancelled).
* Add migration RetireLegacyTaskStatus that rewrites existing rows:
manual/draft -> idle, planning -> idle+planning_phase=active,
planned -> idle+planning_phase=finalized, waiting -> queued+blocked_by
derived from sort_order via a CTE with LAG().
* Reroute every call site that compared/set legacy values to the new
three-field model (Status + PlanningPhase + BlockedByTaskId), including
the planning repo helpers, MCP services, the planning chain coordinator,
and the UI view-models. TaskRowViewModel now exposes PlanningPhase to
drive the planning badge.
* Refresh Worker/CLAUDE.md and Data/CLAUDE.md, the docs/plan.md status
section, and the planning verification notes in docs/open.md.
mika kuns