Fixes issue 3: the host-agent console showed OCR results but never real
UI-tree data, because _ui_tree_nodes() checked for a get_ui_tree/ui_tree
tool action that has never existed anywhere in the codebase.
- storage/timeline.py: add a ui_tree_results field to TimelineRecord and
Timeline.append(), mirroring the existing ocr_results field.
- runtime/task.py: _append_timeline() now extracts scene.elements with
source == "ui" into ui_tree_results (scene_builder.build_scene() already
preserved these; they were just never persisted).
- host_agent/web/app.py: _ui_tree_nodes() reads the new field directly
instead of the dead tool-action check. New _overlay_payload() exposes
each step's scene dimensions and fused element list for client-side
rendering.
- task_detail.html: adds a toggle to overlay OCR (orange) and UI-tree
(blue) bounding boxes on the before-action screenshot, plus a visual
marker for the actually executed action (tap circle, or an animated
swipe path) using an SVG viewBox so no manual coordinate-scaling JS is
needed. Legacy/incomplete records degrade to no overlay, never an error.
Also corrects openspec/specs/runtime-task-evidence and
host-agent-console-task-pages, which had encoded the same nonexistent-tool
assumption, via the new host-agent-console-visual-evidence change.
600 tests passing; ruff/compileall/openspec validate all clean.
