CLI: `add` accepts undocumented flags like `--context` and `--rationale` silently

[Mearman]

Problem

sysprom add --help only lists --scope, --option, --json, and --dry-run as options. However, additional flags like --name, --description, --context, and --rationale are accepted and work correctly — they're just not documented in the help output.

Reproduction

sysprom add --help
# Output shows: --scope, --option, --json, --dry-run — no --name, --description, --context, --rationale

sysprom add decision --name "Example" --context "Some context" --rationale "Some rationale"
# Works — context and rationale are set on the node

Expected behaviour

All accepted flags should be listed in sysprom add --help, ideally with notes on which flags apply to which node types (e.g. --context and --rationale for decisions, --element for realisations).