feat: Add extensible multi-pipeline integration system

This commit implements a plugin-like pipeline architecture with:

Pipeline Core Package (packages/pipeline-core/):
- BasePipeline abstract class all pipelines implement
- PipelineRegistry for database-backed discovery/management
- PipelineRunner for execution with status tracking
- DashboardConfig contracts for dynamic widget definitions

Database Migration (006_pipeline_registry.sql):
- pipeline.registry table for registered pipelines
- pipeline.executions table for execution history
- Views for execution stats and monitoring

ReviewIQ Pipeline Refactor:
- Implements BasePipeline interface
- Adds get_dashboard_config() with widget definitions
- Adds get_widget_data() methods for all dashboard widgets
- Maintains backward compatibility with Pipeline alias

Generic Pipeline API (api/routes/pipelines.py):
- GET /api/pipelines - List all registered pipelines
- GET /api/pipelines/{id} - Pipeline details
- POST /api/pipelines/{id}/execute - Execute pipeline
- GET /api/pipelines/{id}/dashboard - Dashboard config
- GET /api/pipelines/{id}/widgets/{w} - Widget data
- GET /api/pipelines/{id}/executions - Execution history

Frontend Dynamic Dashboard System:
- DynamicDashboard component renders from config
- WidgetRegistry maps types to components
- Widget components: StatCard, LineChart, BarChart,
  PieChart, DataTable, Heatmap
- Pipeline API client library

Frontend Pipeline Pages:
- /pipelines - List all registered pipelines
- /pipelines/[id] - Dynamic dashboard for pipeline
- /pipelines/[id]/executions - Execution history
- Pipelines nav item in Sidebar

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

web/components/dashboard/WidgetRegistry.tsx

@@ -0,0 +1,98 @@
+'use client';
+
+import type { ComponentType } from 'react';
+import type { WidgetConfig, WidgetType, WidgetData } from '@/lib/pipeline-types';
+import { StatCard } from './widgets/StatCard';
+import { LineChartWidget } from './widgets/LineChart';
+import { BarChartWidget } from './widgets/BarChart';
+import { PieChartWidget } from './widgets/PieChart';
+import { DataTableWidget } from './widgets/DataTable';
+import { HeatmapWidget } from './widgets/Heatmap';
+
+// Common widget props
+export interface WidgetComponentProps {
+  config: WidgetConfig;
+  data: WidgetData | null;
+  loading: boolean;
+  error?: string;
+  onRefresh?: () => void;
+  onPageChange?: (page: number) => void;
+  currentPage?: number;
+}
+
+// Widget component type
+type WidgetComponent = ComponentType<WidgetComponentProps>;
+
+/**
+ * Registry mapping widget types to their React components.
+ */
+const WIDGET_COMPONENTS: Record<WidgetType, WidgetComponent> = {
+  stat_card: StatCard as WidgetComponent,
+  line_chart: LineChartWidget as WidgetComponent,
+  bar_chart: BarChartWidget as WidgetComponent,
+  pie_chart: PieChartWidget as WidgetComponent,
+  table: DataTableWidget as WidgetComponent,
+  heatmap: HeatmapWidget as WidgetComponent,
+  // Placeholder for unimplemented types
+  area_chart: LineChartWidget as WidgetComponent, // Use line chart as fallback
+  gauge: StatCard as WidgetComponent, // Use stat card as fallback
+};
+
+/**
+ * Get the component for a widget type.
+ */
+export function getWidgetComponent(type: WidgetType): WidgetComponent | null {
+  return WIDGET_COMPONENTS[type] || null;
+}
+
+/**
+ * Check if a widget type is supported.
+ */
+export function isWidgetTypeSupported(type: string): type is WidgetType {
+  return type in WIDGET_COMPONENTS;
+}
+
+/**
+ * Render a widget based on its configuration.
+ */
+export function renderWidget(
+  config: WidgetConfig,
+  data: WidgetData | null,
+  loading: boolean,
+  error?: string,
+  onRefresh?: () => void,
+  onPageChange?: (page: number) => void,
+  currentPage?: number
+): React.ReactNode {
+  const Component = WIDGET_COMPONENTS[config.type];
+
+  if (!Component) {
+    return (
+      <div className="bg-white dark:bg-gray-800 rounded-lg border border-gray-200 dark:border-gray-700 p-4">
+        <p className="text-red-500">Unknown widget type: {config.type}</p>
+      </div>
+    );
+  }
+
+  return (
+    <Component
+      config={config}
+      data={data}
+      loading={loading}
+      error={error}
+      onRefresh={onRefresh}
+      onPageChange={onPageChange}
+      currentPage={currentPage}
+    />
+  );
+}
+
+// Export widget components for direct use
+export {
+  StatCard,
+  LineChartWidget,
+  BarChartWidget,
+  PieChartWidget,
+  DataTableWidget,
+  HeatmapWidget,
+};