release: bump version to 0.51.0

docs/technical/en/quickstart.md

@@ -57,7 +57,7 @@ After startup, the key URLs are:
 | Earth | `http://localhost:3000/earth` | Public 3D Earth visualization |
 | Console | `http://localhost:3000/admin` | Admin console (login required) |
 | Docs | `http://localhost:3000/docs` | Usage docs are public; developer and operations docs require Gatekeeper groups |
-| AI Playground | `http://localhost:3000/playground` | AI debugging (login required) |
+| AI | `http://localhost:3000/ai` | Model provider, tool, and testbench entry (login required) |
 | Backend API Docs | `http://localhost:8000/docs` | FastAPI / OpenAPI interface docs |
 
 If the default ports are taken, specify custom ports:
@@ -114,6 +114,7 @@ First-time inspection checklist:
 - `/datasources`: data source directory and collection triggers; endpoint, headers, and credentials are configured under `/settings` collector settings
 - `/data`: collected data
 - `/bgp`: BGP situational view
+- `/ai`: AI page for model providers, WebSearch-style tools, and the testbench
 - `/alerts/system`: system alerts
 - `/settings`: system configuration