[DGX Station][CLI&UX] nemohermes exec returns exit code 0 after an iteration-limit failure

## NVBug 6471146

**Description**

When Hermes reaches the configured maximum iteration count before completing a tool-driven request, `nemohermes exec` returns exit code 0 even though the requested operation and output artifact are incomplete.

The post-limit summary can also contain a new tool call that is never executed because the agent loop has already stopped. This makes the successful process status inconsistent with the actual task result.

**Steps to Reproduce**

1. Create a Hermes sandbox and configure an MCP server.
2. Submit a tool-driven request that cannot complete within the configured iteration limit:
```
nemohermes {sandbox} exec --timeout 1200 -- \
hermes chat -Q --max-turns 15 -q \
"Use the configured Blender MCP server to complete an OVRTX render and verify the output artifact."
```
3. Allow the request to reach the maximum iteration count.
4. Record the final summary and shell exit code.

**Expected Result**

- Non-zero exit code or explicit incomplete status
- Summary should not contain unexecuted tool calls
- Automation should distinguish completed vs incomplete runs

**Actual Result**

`nemohermes exec` returns exit code 0. The summary contains a proposed tool call that was never executed. The requested artifact is absent.

**Environment**

- DGX Station, Ubuntu 24.04 aarch64
- NemoClaw 0.0.84, Hermes Agent 0.18.0
- Model: Nemotron 3 Ultra 550B

Start by reproducing the iteration-limit case with `nemohermes exec` and the shown `hermes chat` command, recording the shell status and final summary. Trace the CLI entry point that handles the stopped agent loop and summary, then verify that incomplete runs return a non-zero or explicit incomplete status and do not report an unexecuted tool call.

Written by the indexing model from the issue text.