rate-limit-guard: unwrap-before-compose logic drifted behind context-guard's fixed version #3602

Observation

Surfaced during the Phase 2c twin dedup: the two guards' "Unwrap before you compose" logic is twin-but-drifted, and behaviorally so — rate-limit-guard's setup SKILL.md (~L171) still treats bare quoting as a sh -c-wrap trigger, the exact bug context-guard's rewritten guard (~L264-318) fixed with the type -P builtin test. The Phase 2c dedup deliberately covered only the legacy-statusline detection spoke; this second twin needs its own fix-then-dedupe pass (fix rate-limit-guard to context-guard's semantics, then extract via the sync registry like legacy-statusline-detect).

Follow-up from the customization-consistency program's Phase 2c.