feat(reviewiq): Add AI synthesis support to dashboard components

Frontend:
- Add Synthesis type with action plan, insights, annotations
- ExecutiveSummary: Accept synthesis prop for AI narrative
- SentimentPie: Accept insight prop for contextual explanation
- IntensityHeatmap: Accept insight + highlightDomain props
- TimelineChart: Accept insight + annotations props
- All components gracefully degrade when synthesis is null

Backend:
- Add Stage 4: Synthesize for generating AI narratives
- Gathers context from classified spans
- Generates executive narrative, section insights, action plan
- Produces timeline annotations and marketing angles
- Stores synthesis in pipeline.executions table

Components show AI insights with purple gradient styling when available,
fall back to existing behavior when synthesis is not yet generated.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

web/components/reviewiq/index.ts

@@ -0,0 +1,36 @@
+/**
+ * ReviewIQ Dashboard Components
+ * Export all components for easy imports.
+ */
+
+// Main dashboard
+export { ReviewIQDashboard } from './ReviewIQDashboard';
+
+// Supporting components
+export { FilterBar } from './FilterBar';
+export { DashboardSkeleton, DashboardError, DashboardEmpty } from './DashboardSkeleton';
+
+// KPI components
+export { KPICard } from './kpi/KPICard';
+export { KPISection } from './kpi/KPISection';
+export { DomainScores } from './kpi/DomainScores';
+
+// Insights components
+export { ExecutiveSummary } from './insights/ExecutiveSummary';
+export { StrengthsWeaknesses } from './insights/StrengthsWeaknesses';
+export { OpportunityMatrix } from './insights/OpportunityMatrix';
+export { RatingSimulator } from './insights/RatingSimulator';
+
+// Chart components
+export { SentimentPie } from './charts/SentimentPie';
+export { URTBarChart } from './charts/URTBarChart';
+export { IntensityHeatmap } from './charts/IntensityHeatmap';
+export { TimelineChart } from './charts/TimelineChart';
+
+// Table components
+export { IssuesTable } from './tables/IssuesTable';
+export { IssueDetailModal } from './tables/IssueDetailModal';
+export { SpansTable } from './tables/SpansTable';
+
+// Types
+export * from './types';