saas-dr: dashboard widget surfacing SaaS incident counts and recent activity

[dcoln25-writer]

Phase 2 follow-up.

The dashboard description in apps/web/components/dashboard/dashboard-page.tsx mentions incidents but no actual incident metrics or recent-incident list are rendered. Operators have to navigate to /incidents to see anything.

Scope

• New card section on the dashboard:
  • Metrics row: open / investigating / contained-or-resolved / critical-active counts. Reuse saasIncidentMetrics (the same source the incidents-list page uses).
  • Recent incidents list: latest 5 incidents by last_activity_at with severity, status, assignee, and a deep-link.
  • Pending response actions widget: latest 3-5 response actions still in PROPOSED/APPROVED with action kind, target, and a link to the incident.
• Skeleton states matching the rest of the dashboard.
• Empty states explain how to open the first incident.

Acceptance

• Lighthouse-comparable load: incident metrics fetched in parallel with the existing metrics call (no waterfall).
• Empty / loading / error states all rendered.
• Tenant isolation honored (already enforced server side).