docs: Debug smolagents example incomplete response and serialization warning

[planetf1]

Context

The smolagents interop example in architecture-vs-agents.md produces an incomplete response and a serialization warning when run. The missing pip install smolagents note has been added (PR #601), but the runtime behaviour still needs investigation.

Raised in PR #601 review:

• E5 — comment: Incomplete response and serialization warning after installing smolagents

What needs to happen

1. Run the smolagents example end-to-end and capture the actual output
2. Determine if the incomplete response is a model issue (granite4:micro too small for agent tasks), a code issue, or expected behaviour
3. Fix the example code or adjust the model recommendation
4. Address the serialization warning
5. Update the doc with working output

Files

• docs/docs/concepts/architecture-vs-agents.md (smolagents section)

Acceptance criteria

• Example runs without warnings
• Output is complete and meaningful
• Sample output included in the doc