feat(deploy): add per-container kind within pods [SLIP-75]

[mitchelljphayes]

Support mixed HTTP + worker containers within a single pod deploy.

• Per-container kind ('http' default, 'worker') on route entries in slip.toml
• HTTP containers: HTTP health check, failures block deploy
• Worker containers: container_is_running() check, failures are warnings
• Deploy succeeds if all HTTP containers pass (workers can fail)
• restartPolicy: OnFailure injected when workers present
• Caddy routes only created for HTTP containers
• 9 new tests (380 total)

SLIP-75