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

Claude-Session: https://claude.ai/code/session_01RFrWpXc1BsqfrFYMbyDusJ

.github/workflows/inactive.yaml

@@ -4,7 +4,7 @@ on:
     - cron: "0 8 * * *"
 jobs:
   manage-inactive:
-    runs-on: ubuntu-latest
+    runs-on: zenlm-build-linux-amd64
     permissions:
       actions: write
       issues: write

.github/workflows/test.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: zenlm-build-linux-amd64
     strategy:
       matrix:
         python-version: ["3.14"]

.github/workflows/translate.yaml

@@ -15,7 +15,7 @@ jobs:
       issues: write
       discussions: write
       pull-requests: write
-    runs-on: ubuntu-latest
+    runs-on: zenlm-build-linux-amd64
     steps:
       - uses: actions/checkout@v3
       - uses: lizheming/github-translate-action