[CI] Rename basic CI stage-a/b/c -> base-a/b/c for symmetry with extra CI (#25420)

.github/actions/check-pr-test-health/action.yml

@@ -1,4 +1,4 @@
-name: Check Stage Health
+name: Check PR Test Health
 description: Fail fast if any job in the current workflow run has already failed, or if the lint check (from lint.yml) has failed. Auto-skips for scheduled runs. The jobs-failed check (but not the lint check) is bypassed when the PR carries the `bypass-fastfail` label.
 
 inputs:
@@ -10,16 +10,16 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Check stage health
+    - name: Check PR test health
       uses: actions/github-script@v7
       env:
-        SKIP_STAGE_HEALTH_CHECK: ${{ env.SKIP_STAGE_HEALTH_CHECK }}
+        SKIP_PR_TEST_HEALTH_CHECK: ${{ env.SKIP_PR_TEST_HEALTH_CHECK }}
       with:
         github-token: ${{ inputs.github-token }}
         script: |
           // Skip when explicitly requested via env var (e.g. release branch cut)
-          if (process.env.SKIP_STAGE_HEALTH_CHECK === 'true') {
-            core.info('Skipping health check (SKIP_STAGE_HEALTH_CHECK=true)');
+          if (process.env.SKIP_PR_TEST_HEALTH_CHECK === 'true') {
+            core.info('Skipping health check (SKIP_PR_TEST_HEALTH_CHECK=true)');
             return;
           }
 
@@ -83,12 +83,12 @@ runs:
             // match so we cover both inline + reusable forms without confusing
             // 'h20' with the 'h200' prefix.
             const baseName = j.name.split(/[ /]/)[0];
-            if (baseName === 'stage-c-test-8-gpu-h20') {
+            if (baseName === 'base-c-test-8-gpu-h20') {
               return false;
             }
             // If the failing step is the health check, it's a cascade — skip it
             const failedStep = (j.steps || []).find(s => s.conclusion === 'failure');
-            if (failedStep && (failedStep.name.includes('check-stage-health') || failedStep.name.includes('Check stage health'))) {
+            if (failedStep && (failedStep.name.includes('check-pr-test-health') || failedStep.name.includes('Check PR test health'))) {
               return false;
             }
             return true;

.github/actions/wait-for-jobs/action.yml

@@ -3,12 +3,12 @@ description: Poll and wait for specified jobs in the current workflow run to com
 
 inputs:
   stage-name:
-    description: 'Human-readable stage name for log messages (e.g. "stage-a")'
+    description: 'Human-readable stage name for log messages (e.g. "base-a")'
     required: true
   jobs:
     description: |
       JSON array of job specs to wait for. Each element is either:
-        - a string: exact job name (e.g. "stage-a-test-1-gpu-small")
+        - a string: exact job name (e.g. "base-a-test-1-gpu-small")
         - an object { "prefix": "...", "expected_count": N }: for matrix jobs
     required: true
   max-wait-minutes: