feat: add AI Digital Employee agent orchestrator with pipeline tracking

- New AgentPipeline model with JSONB pipeline_data for stages/leads/summary
- AgentOrchestrator service chains DiscoveryService search→analyze→outreach→auto-save
- 3 new API endpoints: POST /agent/start, GET /agent/pipelines, GET /agent/{id}
- Full Agent dashboard Vue component with stats, pipeline grid, leads table, outreach preview
- Sidebar redesigned with AI Agent as primary entry point
- Updated PROGRESS.md, AGENTS.md, DATABASE_SCHEMA.md with latest state

backend/app/api/v1/__init__.py

@@ -28,6 +28,7 @@ from . import referral
 from . import admin_search
 from . import search
 from . import admin_ai
+from . import agent
 
 __all__ = [
     'auth', 'marketing', 'translate', 'customer', 'quotation', 'whatsapp',
@@ -35,5 +36,5 @@ __all__ = [
     'onboarding', 'notification', 'feedback', 'payment', 'interaction',
     'silent_pattern', 'training', 'followup', 'ai_assistant', 'discovery',
     'discovery_record', 'certification', 'invoice', 'usage', 'referral',
-    'admin_search', 'search', 'admin_ai'
+    'admin_search', 'search', 'admin_ai', 'agent'
 ]