feat: include node information in upsert command response (#1099)

## Summary

Enhances the upsert (put) command to include node information in the
JSON response, allowing users to see which node was used for the
operation.

**Before:**
```json
{
  "id": "sh7lxf0xxkyekj70632czg2c",
  "completed": true,
  "queued": false
}
```

**After:**
```json
{
  "id": "sh7lxf0xxkyekj70632czg2c",
  "node": "personal",
  "completed": true,
  "queued": false
}
```

## Changes

- Modified `UpsertCommand.cs` to include `node.Id` in response output
- Node information is already available from the `Initialize()` method
- Only affects non-quiet verbosity mode (quiet mode still outputs just
the ID)

## Testing

- ✅ All 301 tests pass (192 Main.Tests + 109 Core.Tests)
- ✅ 0 skipped tests
- ✅ Code coverage: 81.99% (exceeds 80% threshold)
- ✅ Build: 0 warnings, 0 errors

## Stats

- **Files changed:** 1
- **Lines added:** 1
- **Lines removed:** 0
- **Tests added:** 0 (existing tests validate behavior)

## Breaking Changes

None - this is a backward-compatible enhancement that adds information
to the response.

Co-authored-by: Amplifier <[email protected]>

Author: dluc

src/Main/CLI/Commands/UpsertCommand.cs

@@ -108,6 +108,7 @@ public override async Task<int> ExecuteAsync(
                 formatter.Format(new
                 {
                     id = result.Id,
+                    node = node.Id,
                     completed = result.Completed,
                     queued = result.Queued,
                     error = string.IsNullOrEmpty(result.Error) ? null : result.Error