security: No input validation on deployment names or port numbers

[nfebe]

Problem

Deployment Names

Deployment names are used directly in filesystem paths and compose file generation without validation. A crafted name like ../../../etc could cause path traversal.

Port Numbers

internal/api/server.go (lines ~2231-2242) uses HostPort directly in compose generation:

fmt.Sprintf("ports:\n      - \"%s:%d\"", opts.HostPort, containerPort)

No range check (0-65535), format validation, or privileged port restriction.

Impact

• Path traversal leading to arbitrary file read/write
• Invalid port assignments causing failed deployments or privilege escalation

Proposed Fix

// Deployment name validation
var validName = regexp.MustCompile(`^[a-z0-9][a-z0-9_-]{0,49}$`)

// Port validation
func validatePort(port string) error {
    p, err := strconv.Atoi(port)
    if err != nil || p < 1 || p > 65535 {
        return fmt.Errorf("invalid port: %s", port)
    }
    return nil
}

Also reject reserved deployment names (nginx, certbot, agent, etc.).