fix(cli): accept required body fields from flags

[ysyneu]

Summary

• let generated required request fields come from positional args, typed flags, or --data
• keep scalar extra-argument rejection and typed-flag override semantics
• regenerate every affected command from the shared cligen source

Audit evidence

Production sessions exposed version-skew around channel escalate-rule-list: the command help advertised --channel-id, while the target branch positional validator rejected that source before request assembly. The same contradiction affected every generated required body field.

Verification

• make GOLANGCI_LINT=/tmp/fc-safari-audit-tools/golangci-lint-current (fmt, lint, race tests, build)
• make check-cards
• focused scalar and variadic source tests for positional / typed flag / --data
• cligen regenerated twice with zero diff drift
• /simplify --uncommitted
• /review-to-main --uncommitted
• /review-to-main