Fixes #72 - adds both vs all distinction for teardown behavior.

Changes:

• teardown both - removes central + sensor, keeps operator (fast iteration)

• teardown all - removes central + sensor + operator (full cleanup)

• Default teardown is now all for complete cleanup

• Teardowns run in parallel for better performance

• Operator deployment is now explicit instead of hidden in central/sensor deployment

• Added app.kubernetes.io/managed-by=roxie label to operator namespace

  Breaking change: Default teardown behavior changed from leaving operator behind to removing it. Use teardown both for the old behavior.

Manual testing:

Default behavior (all):

• ./roxie deploy --resources=small → deployed central + sensor + operator
• ./roxie teardown → removed all three including rhacs-operator-system namespace

both vs all distinction:

• ./roxie deploy all --resources=small → deployed everything
• ./roxie teardown both → central/sensor resources deleted, operator kept running
• ./roxie teardown all → operator removed

Single namespace mode:

• ./roxie deploy --single-namespace --resources=small → stackrox namespace labeled with managed-by=roxie
• ./roxie teardown --single-namespace → cleaned up including operator

Parallel teardown verified - all three components started teardown simultaneously (logged at 00:01), finished independently.