feat(live): validate and swap compiled shaders between guest frames

feat(x86): prove emitted instruction execution and return-frame consumption

feat(branches): compile conditionals to validated forward jumps

feat(allocator): retain intermediates in registers and spill nested values

test(compiler): exhaustively compare optimised small expressions

test(native): isolate generated code execution in child processes

feat(checker): validate native stack and register effects

feat(frontend): accept digits after identifier prefixes

perf(optimiser): collapse conditionals with identical branches

perf(optimiser): eliminate absorbing arithmetic and bitwise expressions

perf(optimiser): fold neutral arithmetic and bitwise operations

feat(compiler): add verified pixel compiler and templeos runner