feat(mcp): connect authenticated AquaPortal tools to Vocero (#1)

Vocero needs to query AquaPortal on behalf of the caller selected by the existing phone link. This adds server-owned conversations and MCP tool execution for voice and HTTP reasoning while leaving the speech pipeline unchanged.

Release notes:

- Added browser-bound conversations that keep backend credentials server-side and isolate callers.
- Connected the eight-tool AquaPortal catalog through authenticated Streamable HTTP with full input schemas and structured results.
- Added bounded multi-step tool execution with cancellation, expiry, and stale-result protection.
- Updated browser bootstrap, tool progress, reasoning headers, and conversation cleanup.
- Disabled legacy unscoped content preloads in MCP mode and documented configuration and deployment constraints.
- Preserved disabled-mode contracts and added local SDK, WebSocket, and browser regression coverage.

Reviewed-on: AquaPortal/s2s#1

vocero-api/vocero_api/realtime/proxy.py

@@ -16,12 +16,16 @@ from vocero_api.core import urls as core_urls
 from vocero_api.providers import apipilot as providers_apipilot
 from vocero_api.providers import caller as providers_caller
 from vocero_api.realtime import events as realtime_events
+from vocero_api.realtime.mcp_proxy import realtime_mcp_proxy
 from vocero_api.services import context as services_context
 from vocero_api.services import tool_context as services_tool_context
 
 
 async def realtime_proxy(ws: WebSocket) -> None:
     """Relay the browser's same-origin realtime WebSocket to the configured upstream."""
+    if settings.S2S_MCP_URL:
+        await realtime_mcp_proxy(ws)
+        return
     client_ip = ws.client.host if ws.client else "?"
     if not settings.S2S_PROXY_TARGET:
         app_logging.logger.debug("[EXT][S2S-PROXY] client=%s rejected: S2S_PROXY_TARGET not configured", client_ip)