[Bug]: jira workitem query caps results at 100 with no truncation signal

### TWG CLI version
1.2.6

### Operating system
Ubuntu 24.04 (WSL2)

### Command or agent request
Run against a project with more than 100 matching issues:

```bash
twg jira workitem query --jql 'project = ABC' --limit 200 -o json
```

### Expected behavior
Either the requested number of results, or an explicit signal that the result is partial.

1.2.6 introduced this for documents: "Document pagination: ... return resumable partial results with exit code 3 instead of discarding completed work." The same signal on work item queries would make partial results detectable.

### Actual behavior
100 issues returned for `--limit 200`. Exit code 0, `warnings` empty. Without `--limit`, the same query returns 50.

`pageInfo.hasNextPage: true` and `nextCursor` are present in the payload file, but the agent-mode envelope written to stdout does not surface them.

A caller that requested 200 and received 100 has no in-band signal distinguishing a truncated result from a complete one.

Start with `twg jira workitem query --jql 'project = ABC' --limit 200 -o json` against a project with more than 100 matching issues, and compare the agent-mode stdout envelope with the payload file. Trace how `pageInfo.hasNextPage` and `nextCursor` are handled; done means the requested results are returned or a detectable partial-result signal is emitted instead of exit code 0 with empty warnings.

Written by the indexing model from the issue text.