Remove all @import("zig_internals") from stage0/ so that test_obj
compilation is independent of the Zig compiler (~6min). The sema
comparison now uses text-based dumpers:
- Zig side (src/verbose_air.zig): compiles source through the full Zig
pipeline, captures verbose_air output, exports zig_dump_air() as a C
function. Compiled as a separate dumper_obj that is cached
independently.
- C side (stage0/verbose_air.c): formats C Air structs to text in the
same format as Zig's Air/print.zig.
Changing stage0 code no longer triggers Zig compiler recompilation:
C compile + cached test_obj + cached dumper + link = seconds.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
