[BUG] `az boards` query: WIQL @project macro returns empty result (exit 0) while literal project works

## Summary
`az boards query` returns an empty response with exit code `0` when WIQL uses `@project` in `[System.TeamProject] = @project`.

Using the same query with the literal project name returns results.

## Versions
- Azure CLI: `2.76.0`
- Azure DevOps extension: `1.0.2`
- OS: Linux (WSL2)

## Repro

```bash
az devops configure --defaults organization="https://dev.azure.com/" project=""

az boards query --wiql "SELECT [System.Id] FROM WorkItems WHERE [System.TeamProject] = @project AND [System.State] = 'Technical Refinement'"
echo $?
```

## Actual
- Command exits `0`
- No output returned

## Control (works)

```bash
az boards query --wiql "SELECT [System.Id] FROM WorkItems WHERE [System.TeamProject] = '' AND [System.State] = 'Technical Refinement'"
```

- Returns expected work item list

## Expected
`@project` should resolve to the configured default project and return the same result set as the literal project value.

## Notes
- Local config contains project exactly as expected (no hidden/trailing chars).
- This appears specific to `@project` expansion in this WIQL context.