more versitile nix settup

Author: Geometer1729

.github/actions/build/action.yml

@@ -1,7 +1,6 @@
 name: Build o1js
 description: 'All of the building steps for o1js'
 
-
 permissions:
   contents: write
 
@@ -16,9 +15,22 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - name: Set up Nix
+    - name: Install zstd if needed
+      shell: bash
+      run: command -v unzstd || (sudo apt-get update && sudo apt-get install -y zstd)
+    - uses: nixbuild/nix-quick-install-action@v30
+      continue-on-error: true
+      with:
+        nix_conf: |
+          keep-env-derivations = true
+          keep-outputs = true
+          extra-substituters = https://storage.googleapis.com/mina-nix-cache
+          extra-trusted-public-keys = nix-cache.minaprotocol.org:fdcuDzmnM0Kbf7yU4yywBuUEJWClySc1WIF6t6Mm8h4= nix-cache.minaprotocol.org:D3B1W+V7ND1Fmfii8EhbAbF1JXoe2Ct4N34OKChwk2c= mina-nix-cache-1:djtioLfv2oxuK2lqPUgmZbf8bY8sK/BnYZCU2iU5Q10=
+    - name: Fallback to persistant nix
+      # only available on some runners
       shell: bash
-      run: echo "PATH=$PATH:/nix/var/nix/profiles/default/bin" >> $GITHUB_ENV
+      run: command -v nix || echo "PATH=$PATH:/nix/var/nix/profiles/default/bin" >> $GITHUB_ENV
+
     - name: Disable smudging
       shell: bash
       run: echo "GIT_LFS_SKIP_SMUDGE=1" >> $GITHUB_ENV

.github/workflows/checks.yml

@@ -18,7 +18,7 @@ permissions:
 
 jobs:
   Prepare:
-    runs-on: [sdk-self-hosted-linux-amd64-build-system]
+    runs-on: self-hosted
     steps:
       - name: Checkout repository with submodules
         uses: actions/checkout@v4
@@ -72,7 +72,7 @@ jobs:
       - name: Run Oxlint
         if: steps.get_changed_files.outputs.files_changed == 'true'
         run: xargs npm run lint:strict < changed_files.txt
-      
+
       - name: Run codespell
         if: steps.get_changed_files.outputs.files_changed == 'true' && github.event.pull_request.labels.*.name != 'no-typo-check'
         uses: codespell-project/actions-codespell@master
@@ -86,7 +86,7 @@ jobs:
   Upload-bindings:
     name: upload bindings artifact
     needs: [Prepare]
-    runs-on: [sdk-self-hosted-linux-amd64-build-system]
+    runs-on: self-hosted
     steps:
       - uses: actions/checkout@v4
         with: