Rollback ignores version parameter

[zacharyblasczyk]

Description

In pkg/helm/chart.go:124-127, the Rollback(version int) method accepts a version parameter but never passes it to the Helm rollback action:

func (c *ActionableChart) Rollback(version int) error {
    client := action.NewRollback(c.config)
    return client.Run(c.releaseName)
}

This silently rolls back to the previous release rather than the specified version. If version-targeted rollbacks are ever needed, this will produce incorrect behavior.

Suggested fix

Set the version on the rollback client before running:

func (c *ActionableChart) Rollback(version int) error {
    client := action.NewRollback(c.config)
    client.Version = version
    return client.Run(c.releaseName)
}

Found during review of #147.