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>

api/routes/__init__.py

@@ -6,6 +6,7 @@ This module exports all route modules for easy import into the main server.
 from api.routes.batches import router as batches_router, set_database as set_batches_db
 from api.routes.dashboard import router as dashboard_router, set_database as set_dashboard_db
 from api.routes.admin import router as admin_router, set_database as set_admin_db
+from api.routes.pipelines import router as pipelines_router, set_database as set_pipelines_db
 
 __all__ = [
     'batches_router',
@@ -14,4 +15,6 @@ __all__ = [
     'set_dashboard_db',
     'admin_router',
     'set_admin_db',
+    'pipelines_router',
+    'set_pipelines_db',
 ]