[turinglambdaai]

Parity gap

Linux #33 enables GTK4 native Ctrl/Shift selection, but selected tasks still have no grouped action surface. This adds the same first-stage batch complete / move to list behavior as the Windows #42 toolbar.

Changes

• GTK4 contextual bulk bar appears when at least two task rows are selected. Complete selected and Move to List act on a snapshot of task IDs, not visual row indices.
• Each batch operation uses the shared typed backend API and preserves task text, notes, completion/date fields when moving.
• Global search results now retain task objects in the view model, allowing bulk operations on tasks belonging to other lists, with selection preserved through search result refreshes.
• Rebuild list destination options from the current list snapshot when opening the popover. Avoid forcing a batch-delete without undo.
• Localized action labels use existing i18n strings; update the UX benchmark status.

Dependencies

Stacked on Linux native selection #33. Review together with #34 (theme CSS) and #38 (Linux quick-add safe-save), which are independently based on main; resolve overlapping changes in linux/src/main.cpp before final integration.

QA before merge

• Linux GTK native build and packaged Product Acceptance green
• Ctrl/Shift-select tasks in 工作; batch-complete affects only those selected
• Batch-move from 工作 to 生活 and verify task metadata, completion and persistence after relaunch
• Run the same operations from global search results for cross-list matches
• Test changing lists/search while selection and a backend mutation are in flight
• Theme/language changes update toolbar labels; 100% and 150% scaling remains usable

Scope: Bulk date scheduling, delete/undo and manual parity checks still outstanding. Do not merge or release until integrated validation.