GTR018.1 — Wrap `<command>` in CDATA (partition fix)

Contract: behaviour-preserving.

Claim

Wrapping a pure-text <command> body in CDATA is a parse-level no-op.

Proof

A CDATA section and equivalently-escaped character data parse to the identical .text (XML 1.0 §2.7); Galaxy reads tool XML through its parser, never raw bytes. The cdata_wrappable predicate excludes the one representable-but-lossy case: \r (CDATA cannot carry ; PR #112).

Scope boundary

Mixed-content bodies cannot be CDATA-wrapped at all (XML: a CDATA section cannot contain elements) — the GTR018.2 advisory reports them.