ci: run linux jobs on lux-build-amd64 ARC scale set (no GitHub-hosted builders)

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ env:
 jobs:
   lint:
     name: Lint
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
     - uses: actions/checkout@v5
       with:
@@ -141,7 +141,7 @@ jobs:
 
   security:
     name: Security Scan
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
     - uses: actions/checkout@v5
 

.github/workflows/docs.yml

@@ -18,7 +18,7 @@ concurrency:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - name: Checkout
         uses: actions/checkout@v5
@@ -55,7 +55,7 @@ jobs:
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     needs: build
     steps:
       - name: Deploy to GitHub Pages

.github/workflows/validate_pr.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   validate-pr:
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - name: Checkout repository
         uses: actions/checkout@v5