[M4] SummaryFrame: session history, selection context, and annotation digest

[Korede-TA]

Goal

A dedicated frame that surfaces what the user has been looking at — visited nodes, currently selected/focused nodes, and a digest of their annotations — so they maintain context across long exploration sessions.

What to do

Session history

• Track visited node IDs in order (capped at last 50) in a new history-store or as an addition to selection-store
• "Visited" = any node that was focused (single-click selected) during the session
• History persists within the session but not across reloads

SummaryFrame layout (three sections)

1. History — scrollable list of visited nodes (most recent first), each showing deriveLabel, type badge, and a click-to-refocus action
2. Current selection — derived labels + annotation chips for all nodes in selection-store.selected; if > 5 nodes selected, show count summary ("12 chunks across 3 documents")
3. Context digest — aggregate annotation summary for the current selection:
   • Temporal span: earliest → latest date across all temporal annotations
   • Geographic spread: list of unique location names (top 5 by occurrence)
   • Top entities: person/org names sorted by co-occurrence count

Registration

• Register 'summary' in frame registry and add to ADDABLE_FRAMES in App.tsx

Acceptance criteria

• History list updates as user navigates between nodes
• Clicking a history item refocuses that node across all frames
• Selection digest updates within 100ms of selection change
• Shows meaningful content (not IDs) using deriveLabel