Add el_mem_check() to el_runtime.c: reads ELC_MAX_MEM_MB (default 512),
checks RSS via getrusage (macOS bytes / Linux KB normalised to MB), prints
a clear diagnostic to stderr and exits(1) if exceeded.
Wire it into two places:
- compiler.el: upfront check at --emit-header entry point
- codegen.el: per-function check in the streaming loop after each
el_arena_pop, so runaway growth is caught at the earliest function
boundary rather than after the machine is already dying.
will.anderson
53e0b99d5f