[Bug]: dab update truncates field descriptions at commas

## Expected

Quoted field descriptions should preserve commas.

```
dab update ServerInventory \
--fields.name Environment \
--fields.description "Deployment environment: Prod, Dev, Test, or UAT"
```

### Expected config:

```json
"description": "Deployment environment: Prod, Dev, Test, or UAT"
```

## Actual

The description is truncated at the first comma.

```json
"description": "Deployment environment: Prod"
```

This makes the CLI unreliable for scripting realistic descriptions, especially descriptions that list valid values.

Start by reproducing the `dab update` command shown in the issue with a quoted description containing commas, then trace the CLI handling for `--fields.description`. Done means the generated configuration preserves the complete `Deployment environment: Prod, Dev, Test, or UAT` value instead of truncating it at the first comma.

Written by the indexing model from the issue text.