jspi: retire the asyncify pipeline — knob, post-link tail, binaryen hooks

Phase 8 in the parent repo. Deleted: asyncify-scheduler.js, apply-asyncify.sh,
apply-finalize.sh, inject-dyncall-shims.sh, asyncify-imports/removelist.txt,
the wasm-opt/finalize stub pair, scripts/binaryen-hoist-pass/ (the fork stays
a dormant submodule; removal is a follow-up), bench/wasm-opt-bench.sh (README
marked historical), wasm/shims/context_sleep.cpp, and the sched-context
harness app + Makefile targets.

PCBJAM_ASYNC_BACKEND is gone: build-wx-wasm.sh hardcodes the jspi stamp
(still force-cleans pre-migration trees), build-kicad-target.sh gives editors
the JSPI link surface and the CLIs nothing (they pin ASYNCIFY=0), the stub
dance is replaced by an unconditional .real-restore, build-wasm-test.sh lost
its whole post-link loop, docker/build.sh's postprocess is the ENV shim only,
and Makefile.wasm links every app JSPI with the scheduler shim as a tracked
prerequisite. pcbjam_async_policy.h keys on __EMSCRIPTEN__.

jspi-scheduler.js: wxWasmMainLoopPump dropped from the wrap census (the
export died with the D5 detach); inert [TRACE] instrumentation removed.

CI: wasm-build.yml rewritten for the single-cache pipeline (one output cache
keyed on compile inputs; post-processed bytes cached after the shim);
opt_level input removed from both callers. wasm-cache-hash.mjs inputs now
cover patch-env-shim.mjs + jspi-scheduler.js + jspi-exports.txt.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NDeBaKKhQztd8KiVtHuyXr

.github/workflows/release.yml

@@ -1,10 +1,9 @@
 name: release
 
 # Release pipeline on a vX.Y.Z tag, in order:
-#   1) build  — the SAME wasm-build.yml recipe as CI, at the SAME -O1 asyncify tail
-#               + run the e2e gate. Because the opt level now matches main, this
-#               FINAL-cache-hits main's build and skips the asyncify tail rebuild.
-#               Uploads output/.
+#   1) build  — the SAME wasm-build.yml recipe as CI + the e2e gate. For an
+#               already-built commit this hits main's WASM output cache and
+#               skips the build entirely. Uploads output/.
 #   2) publish-wasm — push the build to the CDN (content-addressed, idempotent)
 #               and write manifest-<tag>.json. The registry now reflects THIS tag.
 #   3) deploy-demo  — build the standalone pinned to that manifest + deploy to
@@ -69,13 +68,12 @@ jobs:
       - id: tag
         run: echo "tag=${{ github.event.inputs.tag || github.ref_name }}" >> "$GITHUB_OUTPUT"
 
-  # 1) Build (-O1, identical to main) + e2e gate. Reuses main's FINAL cache (same
-  #    opt level) so the asyncify tail isn't rebuilt. Uploads the publishable
-  #    output/ as the 'wasm-output' artifact for the publish job.
+  # 1) Build (identical to main) + e2e gate. Reuses main's WASM output cache for
+  #    an already-built commit. Uploads the publishable output/ as the
+  #    'wasm-output' artifact for the publish job.
   build:
     uses: ./.github/workflows/wasm-build.yml
     with:
-      opt_level: "-O1"
       build_3d_viewer: "ON"
       run_tests: true
       upload_output: true