Event Logs UI phase 4: Insights rail #830

Part of #823.
Depends on: #829.
Spec: docs/superpowers/specs/2026-10-08-event-logs-workbench-ui-handoff-design.md (see the section references below).
Design: Claude Design canvas "Event Log Viewer Redesign" (board exports to be attached).

Spec: §5.3, §8.13

Scope (5 files)

• EvtxInsightsRail.tsx (+ test, new): tabs Insights / Details ("Event {id}" when selected).
• EventDiagnosisPanel.tsx: rail variant — finding cards (actionable only, sorted severity → confidence),
  collapsed coverage disclosure with DETAIL_RENDER_CAP, level mix, top event IDs, correlation summary.
• EvtxDetailPane.tsx: summary header (with close button) + "Details | XML" sub-tabs + definition grid + EventData preview,
  existing sections below.
• EventLogWorkspace.tsx: remove top diagnosis card and bottom detail pane; mount rail.

Acceptance

• No finding text is generated by the UI; empty state shows overview headline + "No actionable findings."
• Coverage detail collapsed by default and capped with an omitted count.
• Row click switches to Details and opens the rail if hidden.
• tsc / tests / diff-check / screenshots pass.

Generated by Claude Code