feat: Add alert endpoints to alert_processor service for dashboard

Implemented missing alert endpoints that the dashboard requires for
health status and action queue functionality.

Alert Processor Service Changes:
- Created alerts_repository.py:
  * get_alerts() - Filter alerts by severity/status/resolved with pagination
  * get_alerts_summary() - Count alerts by severity and status
  * get_alert_by_id() - Get specific alert

- Created alerts.py API endpoints:
  * GET /api/v1/tenants/{tenant_id}/alerts/summary - Alert counts
  * GET /api/v1/tenants/{tenant_id}/alerts - Filtered alert list
  * GET /api/v1/tenants/{tenant_id}/alerts/{alert_id} - Single alert

- Severity mapping: "critical" (dashboard) maps to "urgent" (alert_processor)
- Status enum: active, resolved, acknowledged, ignored
- Severity enum: low, medium, high, urgent

API Server Changes:
- Registered alerts_router in api_server.py
- Exported alerts_router in __init__.py

Procurement Client Changes:
- Updated get_critical_alerts() to use /alerts path
- Updated get_alerts_summary() to use /alerts/summary path
- Added severity mapping (critical → urgent)
- Added documentation about gateway routing

This fixes the 404 errors for alert endpoints in the dashboard.

services/alert_processor/app/api_server.py

@@ -8,7 +8,7 @@ from fastapi.middleware.cors import CORSMiddleware
 import structlog
 
 from app.config import AlertProcessorConfig
-from app.api import analytics_router
+from app.api import analytics_router, alerts_router
 from shared.database.base import create_database_manager
 
 logger = structlog.get_logger()
@@ -31,6 +31,7 @@ app.add_middleware(
 
 # Include routers
 app.include_router(analytics_router, tags=["analytics"])
+app.include_router(alerts_router, tags=["alerts"])
 
 # Initialize database
 config = AlertProcessorConfig()