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

.gitignore

@@ -57,4 +57,4 @@ docker-compose.override.yml
 backend/app/services/_bing_search.js
 
 # WeChat mini-program private key
-uni-app/private.key
+uni-app/private.key.omo/