Light-Kanban v1.0.4

Onboarding & archive release.

• Interactive first-run Product Tour: the old centered wizard modal is gone — on first launch a guided overlay runs on the real UI, dims everything except the highlighted control, and follows real clicks/typing across the create dialog, task drawer, settings menu and archive (stable data-tour anchors, auto-placed coachmark clamped to the viewport, bounded missing-target recovery, no dead-ends)
• Guide completion & replay semantics: only walking the tour to the end and pressing Finish writes lk-tour-v1-completed = 1; Skip / Esc / refresh never mark it done, so the tour returns on the next launch; Settings → Guide replays it anytime without clearing the flag
• Archive history open-folder shortcut: every archived task gets a folder icon that opens its workspace folder (same API, icon style and error handling as the task drawer); delete / select-all are unchanged
• Strict tour focus + gray-screen fix: during the tour only the highlighted target (plus the coachmark's own buttons) is clickable — no dialog can be dismissed off-flow; a one-shot guarded missing-target timer fixes the recovery loop found during acceptance
• Frontend unit tests: the tour's decision logic lives in pure functions with 44 vitest cases, wired into make check and CI; the REST API contract is unchanged
• Documentation: README / README_CN, PROGRESS, spec and the manual test checklist updated (new sections P / Q / R); 验收清单.xlsx regenerated

Full spec: .scratch/task-board/spec.md · Manual checklist: docs/manual-test-checklist.md.