Previously, _model_flow_named_custom() returned immediately when a saved
model existed, making it impossible to switch models on multi-model
endpoints (OpenRouter, vLLM clusters, etc.).
Now the function always probes the endpoint and shows the selection menu
with the current model pre-selected and marked '(current)'. Falls back
to the saved model if endpoint probing fails.
Fixes#6862
MCP CallToolResult may include structured_content (a JSON object) alongside
content blocks. The tool handler previously only forwarded concatenated text
from content blocks, silently dropping the structured payload.
This breaks MCP tools that return a minimal human text in content while
putting the actual machine-usable payload in structured_content.
Now, when structured_content is present, it is included in the returned
JSON under the 'structuredContent' key.
FixesNousResearch/hermes-agent#5874
r266-tech