fix(build): host postprocess silently no-ops when emsdk tools are stubbed

build-kicad-target.sh swaps emsdk's wasm-opt/wasm-emscripten-finalize for
no-op stubs (real binaries preserved as *.real) so emcc skips in-link
asyncify — intended for the CONTAINER emsdk, but a host-mode run left the
host tools/emsdk stubbed (since Jun 9). The stub fakes --version and exits 0,
so every local build's host-side finalize/asyncify/-O2 "succeeded" while
doing nothing: output wasm shipped non-asyncified and aborts at boot with
"asyncify_stop_unwind is not a function" (and stayed 122M vs the correct
187M). get-wasm-opt.sh and apply-finalize.sh now prefer the *.real binary
whenever it exists, making the resolution immune to a stubbed emsdk.

Found while validating the CI e2e fix: pcbnew.wasm built this morning could
not boot in any browser. Local artifacts built since Jun 9 may need their
postprocess re-run (apply-finalize.sh + apply-asyncify.sh).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/common/apply-finalize.sh

@@ -13,6 +13,12 @@ PROJECT_ROOT="$(cd "${SCRIPT_DIR}/../.." && pwd)"
 WASM_OPT=$("${SCRIPT_DIR}/get-wasm-opt.sh")
 BINARYEN_BIN=$(dirname "${WASM_OPT}")
 FINALIZE="${BINARYEN_BIN}/wasm-emscripten-finalize"
+# Same stub hazard as wasm-opt (see get-wasm-opt.sh): a host-mode kicad build
+# leaves the emsdk finalize stubbed with the real binary at .real — prefer it,
+# the stub exits 0 having done nothing.
+if [ -x "${FINALIZE}.real" ]; then
+    FINALIZE="${FINALIZE}.real"
+fi
 
 INPUT_WASM="${1:-output/pcbnew.wasm}"
 OUTPUT_WASM="${2:-${INPUT_WASM}}"