38. Calling Plain Rules Directly from Closure Call Sites

• Rules that are never memoized in an ordinary parse and have no captures always end up in invokePlain (change 19), but every call went through call's checks first. Such rules are now marked when the program is built (rule.plain), and the closure backend's call sites call invokePlain directly unless a Document parses (which memoizes them).
• Effect (min of 12 interleaved runs, Apple M3 Max, closure backend): full parses 0–3% faster, recognition 2–4% (JSON 8.4 → 8.1 ms).