53. Projected Repetitions in the Engine and the VMs

• Change 52 in every backend. The analysis moved to project.go (shared by the closure backend, the bytecode compiler and the code generator). It decides from the grammar alone (the engine compiles before type checking): a rule's value is never nil when it has a terminal type or its action makes a struct or returns such a capture, through @error and recursion. The closure backend records the projected map calls and its evaluator takes the list as it is; the VMs mark the repetition with NEXT mode 3 (push the field's slot) and compile the map with (e) => e in place of the projection, so they need no other new instruction.
• With projections in every backend, results produced with them could only be checked against a program without them: the corpus tests now compare every backend and the generated parsers with the engine compiled with noProjections, and fail if the conditions are loosened (a nil field, $n).
• Effect (min of 10 interleaved runs, Apple M3 Max): CSV −22% (closure, 6.1 → 4.7 ms), −16% and −14% (VMs), 14.0 → 8.7 MB; JSON −9% (closure, 13.5 → 12.3 ms), −8% and −6% (VMs); Minilang within noise.