docs: add WebSocket API reference and streaming guide

New pages for the WebSocket server (wss://ws.sharpapi.io/ws):
- API reference with connection lifecycle, message types, close codes
- Streaming guide with SSE vs WebSocket comparison and reconnection patterns
- Updated navigation and streaming overview to link both protocols

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Mlaz-code

pages/api-reference/_meta.json

@@ -35,7 +35,8 @@
     "type": "separator",
     "title": "Streaming"
   },
-  "stream": "Unified Stream",
+  "stream": "SSE Stream",
+  "websocket": "WebSocket Stream",
   "---Account": {
     "type": "separator",
     "title": "Account"