35. Left-Recursion Growth Without Allocation

• Growing the seed of a left-recursive rule allocated a growState per call of the leader and a memo entry on the heap for the seed and for every longer result, instead of taking entries from the memo table's chunks: 84k of the 86k allocations per parse of the left-recursive calculator.
• The grow state is now a value (in the caller's frame, or in the iterative VM's call frame) and the entries come from the memo table's chunks.
• Effect (min of 10 interleaved runs, Apple M3 Max, Arith_LeftRec): full parses 6–9% faster (closure 28.9 → 26.6 ms), recognition 6–10% faster (closure 21.8 → 19.8 ms); 86k → 2.2k allocations.