MitreTechniquePicker dropdown, SimulationList overflow menu,
ExportEngagementButton format menu, and MitreMatrixModal dialog frame
all used bg-canvas as their surface color. With the tinted canvas
(#f3f5f8), these floating surfaces appeared slightly grey instead of
clean white. Switched to bg-paper (#ffffff light / #1f2937 dark).
MitreMatrixModal cell hover (bg-canvas) intentionally preserved —
matrix cells sit on canvas, not on paper.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Add split-button dropdown [Export ▼] on EngagementDetailPage that
downloads engagement as Markdown, CSV, or PDF via
GET /api/engagements/<id>/export?format=md|csv|pdf.
Both halves open the dropdown (no default left-click action).
RBAC-gated with canEditEngagements (admin + redteam only).
Loading state per item, toast on error, click-outside + Escape close.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
