ci: alinear el gate de paridad con arm64 experimental + runtime determinista

- parity-runtime (gate): quita el setup de QEMU y el manejo especial arm64; esos
  casos ahora son skipped-arm64 por default (experimental). Usa -parallel 2 (default
  nuevo del Taskfile) → determinista.
- Nuevo job parity-runtime-arm64-experimental (continue-on-error, PARITY_ARM64=true,
  QEMU): ejercita arm64 sin bloquear el build.
Artefactos ya cubiertos: coverage.out, parity-{contract,network,runtime}.json,
reference-commit.txt.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: aledbf

.github/workflows/go-cli.yml

@@ -102,17 +102,11 @@ jobs:
     runs-on: ubuntu-latest
     needs: lint-and-test
     env:
-      # Los casos update-uid-arm64* arrancan contenedores arm64 reales; en un
-      # runner amd64 se ejecutan emulados vía QEMU (binfmt), que es lento.
       PARITY_RUNTIME_TIMEOUT: "10m"
     steps:
       - uses: actions/checkout@v7
         with:
           submodules: recursive
-      - name: Set up QEMU (emulación arm64)
-        uses: docker/setup-qemu-action@v3
-        with:
-          platforms: arm64
       - uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
@@ -138,6 +132,38 @@ jobs:
       - if: always()
         run: task clean
 
+  # Experimental, NON-gating: arm64 runtime via QEMU emulation. arm64 runtime is
+  # unsupported for now, so its cases are skipped-arm64 in the gate above; this job
+  # exercises them opt-in (PARITY_ARM64=true) without blocking the build.
+  parity-runtime-arm64-experimental:
+    runs-on: ubuntu-latest
+    needs: lint-and-test
+    continue-on-error: true
+    env:
+      PARITY_ARM64: "true"
+      PARITY_RUNTIME_TIMEOUT: "15m"
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          submodules: recursive
+      - name: Set up QEMU (arm64 emulation)
+        uses: docker/setup-qemu-action@v3
+        with:
+          platforms: arm64
+      - uses: actions/setup-go@v6
+        with:
+          go-version-file: go.mod
+      - uses: actions/setup-node@v6
+        with:
+          node-version: "20"
+      - uses: arduino/setup-task@v3
+        with:
+          version: 3.x
+      - run: task reference
+      - run: task parity:runtime
+      - if: always()
+        run: task clean
+
 
   cross-compile:
     runs-on: ubuntu-latest