Added container support to the standalone C (src/printable_binary.c) and the
test-container-c check (clang -O3 -Wall -Wextra) passed — but I pushed without
building the WASM/APE targets. The emscripten build broke: my container block
called buffer_free, which is #ifndef __EMSCRIPTEN__-guarded (so it doesn't
exist in WASM), failing printableBinaryWasm and the default/nix/All Garnix
aggregates that depend on it.
Lesson: src/printable_binary.c is built by clang (native), emscripten (WASM),
AND cosmocc (APE) — each with different defines/guards. Before pushing changes to
it, build nix build .#printableBinaryWasm (and .#printableBinaryApe) locally,
not just the clang container check. A native-clang pass does NOT catch
__EMSCRIPTEN__-guarded-symbol regressions.