[dfinn5-do]

Fixes code samples and app spec schema errors that make examples on docs.digitalocean.com fail when copied or validated. Each change was checked against godo's generated app spec types.

Code samples

• Droplets (curl, Go, Python, Ruby): replace size 1gb with s-2vcpu-4gb and images ubuntu-16-04-x64 and ubuntu-20-04-x64 with ubuntu-26-04-x64. Remove the enable_private_networking action from the curl and Ruby action samples.
• Apps update (curl): wrap the body in {"spec": ...}, as the endpoint requires.
• Apps get logs (curl, four samples): add the required type query parameter.

App spec schema

• Add envs, alerts and features to app_spec, alerts to services, workers and jobs, and the SCHEDULED job kind with its schedule object.
• Logtail destinations require token, not endpoint, which the schema never defined.
• preserve_path_prefix on ingress rules is a boolean, as it already is on routes.

No endpoints added or removed. make lint: 0 errors, 8 existing warnings. With these changes, every app spec example in the docs validates.