feat: add ergonomic declarative CLI declarations

[codeforester]

Summary

• add base_cli_declare as a data-only pipe-delimited table layer over the existing CLI model engine
• accept rows as arguments or stdin/heredocs and order parent commands before children
• document and test the new public API without adding eval or external runtime dependencies

Validation

• bats tests/api-manifest.bats tests/namespace-contract.bats lib/bash/cli/tests/lib_cli.bats
• ./tests/validate.sh

Fixes #302